Coaui  !/\/a^h  Mcthooi^ 


% 


A STUDY  OF  BITUMINOUS  COAL  WASHING  METHODS 


BY 


THOMAS  FRASER 
B.  S.  University  of  Illinois,  1917 


THESIS 


Submitted  in  Partial  Fulfillment  of  the  Requirements  for  the 


Degree  of 


ENGINEER  OF  MINES 


IN 


THE  GRADUATE  SCHOOL 
OF  THE 

UNIVERSITY  OF  ILLINOIS 


1921 


' i 


I U‘ 


'i 

li' 

ii; 


‘U. 


y 


Digitized  by  the  Internet  Archive 
in  2016 


https://archive.org/details/studyofbituminouOOfras 


TABLE  OF  CONTEITTS 


Page 

Suimnary. 8 

Acknowledgement 11 

Chapter  I.-  Introdnction 12 

1.  The  Objects  of  Coal  Washing 12 

2.  Advantages  of  Producing  Clean  Coal 13 

3.  Advantages  of  Using  Clean  Coal 16 

V/ashed  Coal  for  Coking 17 

Washed  Coal  for  Fuel. 19 

Cost  of  Handling  Worthless  Material 20 

Effect  of  High  Ash  Content  on  Thermal  Efficiency..  22 
Decrease  in  Capacity  of  Plant  Equipment 24 

Chapter  II.  - The  Composition  of  Coal  as  it  Affects  V»ashing. ...  26 

4.  Structure  of  the  Coal  Bed.... 26 

5.  Chemical  Forms  of  Impurities  in  Coal 31 

6.  Physical  Forms  of  Impurities  in  Coal 33 

Impurities  Structurally  a Part  of  the  Coal 33 

Segregated  Impurities... 38 

Chapter  III.  - Fundaimental  Principles  of  Coal  Washing 43 

7.  Effect  of  Difference  in  Specific  Gravity 43 

8.  Settling  Ratios.  46 

9.  The  Natural  Middling  Product  in  Raw  Coal 47 

1C,  Relation  of  Specific  Gravity  and  Ash  Content  of  Coal, . , 51 

11.  Relation  Between  Specific  Gravity  and  Sulfur  Content. . . 52 

12.  Distinction  Between  Coal  and  Refuse 54 

Chapter  IV.  - Developmai  t of  the  Practice  of  Washing  Coal, . . . , , 59 

13.  First  Methods  of  Cleaning  Coal  With  Water 59 

14.  Early  Hand  Jigs 61 

15.  Mechanically  Operated  Jigs 63 

16.  Early  Development  of  Coal  Washing  in  America. 68 

Chapter  V.  - Modern  Coal  7/ashing  Machinery 74 

17.  Jigs 74 

Principles  of  Jigging 74 

Jigs  in  Present  Use.,.,. 78 

18.  Trough  Washers S2 

19.  Concentrating  Tables,.. 84 

The  Campbell  Washer 91 


Page 

20*  Classifier  Y/ashers,  94 

21*  Cleaning  Coal  ly  Oil  Flotation 96 

Chapter  VI.  - Methods  Used  in  the  Examination  of  Washers 98 

22.  Standard  Metho  ds 98 

Chemical  Analysis 98 

Screening  Tests 99 

Sink  and  Float  Tests 99 

Sampling  For  Sink  and  Float  Y/ork 112 

22.  Efficiency  Formulae 117 

Lincoln’s  Formula 117 

Delaraater’s  Formulae 118 

Drakely’s  Method 121 

24.  Methods  Used  in  the  Study 124 

Chapter  VII.  - Coal  Washing  Tests...., 128 

25.  Outline  of  the  Experimental  Work 128 

26.  Equipment  Used  in  Experimental  Work ..128 

27.  Comparison  of  the  Work  of  the  Experimental  Table 

Y.'ith  That  of  the  Commercial  Size  Table ,137 

28.  Tests  on  Herrin  Coal. 138 

29.  Bon  Air  Coal 145 

30.  Tests  on  Clover  Run  Coal 154 

31.  Tests  on  Y/est  Virginia  Coal. 163 

32.  Indiana  Ho.  3 Coal........ 178 

Chapter  VIII.  - Conclusions, 187 

33.  Sulfur  Reduction 187 

34.  Ash  Reduction. 191 

35.  Disposal  by  the  V/asher  of  Particles  of  Various 

Specific  Gravities 197 

36.  Efficiencies 203 


LIST  OS'  ILLUSTHATIOIIS 


Page 


Pig^  1.  - Rediuction  in  Heat  Values  Due  to  Presence  of  Ash  in 

Coalt •••*•••*<••••*>*••• 23 

I’ig,  2.  - Specimen  of  Illinois  No,  6 Coal  Showing  Banded 

Structure 27 

I’ig,  3.  - Specific  Gravity  Analysis  of  a Washable  and  a Non- 

washable  Coal. 49 

Fig.  4,  - Curves  Showing  Relation  of  Specific  Gravity  to  Ash 

and  Sulfur  Content 53 

Fig.  5,  - Yield  - Ash  Curve,  Table  V^ashing  Test  on  0”  - 

Coal , 58 

Fig.  6,  - Early  Step  V/asher  Used  in  the  Tarand  Valley 61 

Fig.  7,  - Hand  Jig  Used  in  France  and  Germany  in  1850 62 

Fig.  8,  - Luhrig  Nut  Cos.l  Jig. 65 

Fig.  9.  - Luhrig  Fine  Coal  Jig 67 

Fig.  10.-  Types  of  V/ashers  in  Present  Use 81 

Fig.  11.-  The  Laboratory  Size  Plato  Coal  V/aehing  Table 85 

Fig.  12.-  Underconstruction  of  the  Plato  Table 86 

Fig.  13,-  The  Deis ter-Overs trom  Coal  Washing  Table 87 

Fig.  14,-  The  Campbell  Bumping  Table  as  Used  in  Illinois 92 

Fig.  15.-  Model  Robinson  Washer 94 

Fig,  16.-  The  Delamater  Standard  Sinlc  and  Float  Machine 101 

Fig,  17,-  The  New  Sink  and  Float  Machine 105 

Fig.  18.-  New  Simk  and  Float  Ma,chine  Dissembled  Shov/ing  Parts.  104 
Fig.  19.-  Details  of  B arrel  of  New  Sink  and  Float  Machine,...  105 
Fig.  20.-  Curves  Showing  Variation  From  the  Mean  in  Duplicate 

Sink  and  Float  Tests.. 116 

Fig.  21.-  Coal  V/ashing  Jigs  in  the  Laboratory  of  the  Mining 

Department  of  the  University  of  Illinois 129 

Fig.  22.-  Hartz  Jig  Used  in  the  Experimental  Work.... 130 

Fig,  23.-  Coal  Washing  Tables  in  the  Mining  Laboratory 132 

Fig.  24,-  Coal  Washing  Table  Showing  Special  Equipment  Used...  134 
Fig,  24A.  - Coal  Washing  Table  Shov/ing  Special  Equipment  Used...  135 

Fig,  26.-  Specific  Gravity  Analysis, Herrin  Coal 143 

Fig,  36.-  Theoretical  Yield  Curves,  Herrin  Coal 144 

Fig.  27,-  Theoretical  Yi^tLd  Curves,  Bon  Air  Coal 148 

Fig.  20.-  Theoretical  Yield  Curves,  Clover  Run  Coal 157 

Fig,  29.-  Yield  Curves,  West  Virginia  Coal  0"  - 3/®“  Size.....  171 

Fig.  30.-  Yield  Curves,  Y/est  Virginia  Coal  l/Q"  - Size 173 

Fig.  31,-  Yield  Curves,  West  Virginia  Coal  - 3/8”  Size 17  5 

Fig.  32.-  Theoretical  Yield  Curves,  Indiana  No.  3 Coal 180 

Fig,  33.-  Flov/  Sheet  Deister-Concentrator  Company  Testing  Plant  182 
Fig,  34.-  The  Distribution  Made  by  the  Table  of  Particles  of 

Various  Sizes  and  Specific  Gravities 201 


8 


A STUDY  OF  BITUIdlHOUS  COAL  WASHING  liLETHODS 


SUiCiARY 

The  experimental  work  reported  in  this  study  consisted 
of  the  examination  of  five  coals  from  the  Eastern  and  Central 
fields  to  determine  their  washahility,  and  the  examination  of  a 
nxmiher  of  washeries  in  the  central  field  to  determine  the  -effective- 
ness of  the  methods  used. 

The  coals  used  in  the  experimental  work  were  from  the 
Illinois  No.  6 seam  at  Herrin,  Illinois,  the  Bon  Air  seam  at  Bon 
Air,  Tennessee,  the  Indiana  No.  3 seam  at  Terre  Haute,  Seams  “C“ 
and  '*D“  in  Clearfield  County,  Pennsylvania.,  and  the  Eagle  seam  of 
the  Kanawha  group  in  Boone  County,  West  Virginia* 

The  direct  object  in  the  case  of  the  three  coals  frora 
Tennessee,  Pennsylvania  and  West  Virginia  was  the  reduction  of  the 
sulfur  content  to  produce  a coal  suitable  for  coking  or  for  gas 
manufacture.  The  other  two  coals  presented  problems  in  the  general 
reduction  of  impurities  to  produce  a better  coal  for  the  market. 

The  general  scientific  object  of  the  study  7/a.s  to  deter- 
mine to  what  extent  coals  of  the  types  represented  can  be  cleaned 
by  washing  and  what  are  the  characteristics  of  the  non-washable 
coals  which  cause  difficulty. 

Three  of  the  samples  were  submitted  because  they  present- 
ed exceptional  difficulty  to  sulfur  reduction.  The  West  Virginia 
coal  contained  a large  proportion,  40.5  per  cent,  of  its  sulfur  in 
the  organic  form;  the  Bon  Air  coal,  thou^  low  in  organic  sulfur. 


ctiiofn  r’' 


....  . ..i 


\ 

L '.■ 

.jk'”-  i '\’'*»  *>. 'j" 


Ji’zrr 


. *t.  . . , '.  0;J 

oii  -T*  ***e  j : « : ; 

* 

\t  ii 


YJiA^: 

" ' O'l 

■*•  «•'  \/l  y.s\ 

^ 

t 

■..  '-;jt 

-*  i ■' 

;J.  _■  - ' 

• ^ 

< • 

il  V »’ 

. . 4.  I 

*';  , . Lv' 

. '-i:''  ' f I'  CKi  . 

?>  ^ , 

• 1 - 

' . 
>...  , 

,i  ~ j > ' .1  ' 

IJ  *.T  , .'.• 

' '--D  ^ 'J-.'i/' fri 

a*'.'  .''/r 

? C’C 

- '•/.I 

tr\ 


■ 'rV.'*  ft  ' 


* • t It  \ 

r ‘ ., 


:t  .v-i,a  j " :vnio^ 


'*■ 


0i 


, ■..  r"*'*"' .'.  o ^ Id  mXj'.oc.  ;‘ti  ■'•<' 

.v.'tv-not'r  ni-X  ! fjfjs  . 1:'' ’ » .. 

♦ > .-lo.  •'  '.U;0*D 

tIJ  • - •"  . <»3  f> r':  ■ 


t?4 


-'  I . ' l 
-tj: 


. •■'jf  'TV'.’ ' -J'  Y/*- ^ ■; ‘.;rrc 


■'  1.  ■r 


Ui.  fTO^rr 


J- T ' r.l  wqI  fl^JOfU  . , -ii.';  an 


•i « 

;.  .4'sd 


9 


contained  an  exceptionally  large  part,  37.6  per  cent  of  its  sulfur 
in  the  form  of  fine  particles  of  pyrite  disseminated  throu^  the 
coal  and  the  Indiana  coal  was  high  in  "both  organic  sulfur  and  fine 
disseminated  pyritic  sulfur. 

The  v;ashing  tests  shov/ed  reductions  in  sulfur  content 


Varying  from  12  per  cent  v/ith  the  Indiana  coal  to  63  per  cent  with 
the  Pennsylvania  coal.  The  results  led  to  the  following  conclu- 


sions; 


sulfur 

1.  The  0 rganic^content  is  not  reduced  by  washing. 
In  some  cases  there  is  a larger  percentage  of  organic  sul- 
fur in  the  washed  coal  than  in  the  original  raw  coal  because 
of  the  concentration  due  to  removal  of  inorganic  mineral  mat 
ter  in  the  refuse. 


2.  The  difficulty  in  removing  the  sulfur  from  the 
coals  which  were  designated  as  non-washable  is  due  to  the 
presence  of  a large  percentage  of  organic  sulfur  or  of  fine 
disseminated  pyritic  sulfur  o|*,  more  commonly,  of  both. 


3.  The  easily  desulfurized  coal  contains  a large 
proportion  of  its  sulfur  in  the  form  of  pyrite  deposits  which 
break  free  from  the  coal  and  form  concentra table  high  spe- 
cific gravity  particles. 


4.  The  sulfur  and  ash  do  not  always  occur  together 
in  coal.  A large  amount  of  heavy  mineral  matter  may  be  taken 
out  and  still  leave  the  washed  coal  high  in  sulfur. 

5.  Difficulty  in  removing  the  ash  from  a coal  by 
washing  is  due  either  to  a large  percentage  of  middling  con- 
sisting of  boney  coal,  carbonaceous  shale  or  mixed  particles 
of  shale  and  coal  or  to  a large  proportion  of  fine  inherent 
ash  distributed  through  all  the  coal. 

6.  In  washing  a ravr  coal  containing  fine  material 
the  dust  is  not  cleaned.  If  the  coal  contains  a large  amount 
of  clay  this  goes  into  the  sludge  or  fine  washed  coal  so  that 
it  may  be  higher  in  ash  after  washing  than  before. 

7.  In  treating  a natural  feed  of  a wide  range  of 
sizes  including  the  dust  on  the  concentrating  table  the  loss 
of  good  coal  in  the  refuse  consists  almost  entirely  of  large 
particles  and  the  refuse  in  the  v/ashed  coal  consists  of  small 
particles, mainly  dust,  throu^  100  mesh  in  size. 

8.  In  all  the  table  washing  tests  the  coarser  ma- 
terial heavier  than  1.80  in  specific  gravity,  was  almost  all 


IT 


: t':: 


. j i 


f, 


ijv'U 


r 


f j£vv 

Ota 


■I 


* ^•4.V  \ 

-iJt 

■ .-■ 

mi  or^ 


OCX 


10 


removed  leaving  from  0.4  to  0,5  per  cent  in  the  washed  coal. 
This  percentage  appeared  to  he  about  the  same  for  all  the 
tests  regardless  of  the  proportion  of  this  material  in  the 
feed.  These  results  were  secured  on  coals  ranging  from  7, 5 
to  30.0  per  cent  in  ash.  As  complete  a removal  of  the  heavy 
fraction  of  a very  high  ash  material  such  as  a picking  belt 
refuse  or  an  Alaskan  coal  would  not  be  expected, 

9,  The  washed  coal  generally  contained  a smaller 
percentage  than  the  raw  coal  of  middling  particles  above  1,45 
specific  gravity,  but  as  a rule  the  proportion  of  middling 
particles  of  1,35  to  1.45  was  no  lower  in  the  washed  coal  than 
in  the  raw  coal.  This  refers  to  table  washing  tests  in  v;hich 
an  attempt  was  made  to  secure  the  cleanest  product  possible 
even  with  considerable  sacrifice  in  yield  of  v/ashed  coal  if 
necessary. 

10.  In  the  tests,  the  concentrating  table  was  found 
to  be  a little  more  effective  than  the  jig  in  reducing  the 
ash  and  sulfur  content  of  the  coal.  This  is  largely  due  to 
the  fact  that,  at  the  fine  size  to  which  coal  is  crushed  for 
table  treatment,  the  dirt  particles  are  more  completely  de- 
tached from  the  coal  particles  than  in  the  larger  sizes  at 
which  coal  is  jigged.  It  is  probable  also  that  the  table 
makes  a closer  specific  gravity  separation  than  the  jig. 

11.  In  preparing  coal  for  coking,  where  fine  size  is 
not  objectionable,  the  ta-ble  may  be  used  to  advantage.  In 
preparing  coal  for  fuel,  the  greater  reduction  in  ash  and 
sulfur  is  more  than  offset  by  the  disadvantage  of  fine  size. 


9 ^ 


I 


, ■ K 


. ' JL' . . • »;  - 

i.-->  ;i»  ■ j 

* , 


f :•  • ■ l 


k. 


i .t* 


iwr 


■•x::  1 
• v.io 

^ I 


:.A  T.'  • .r 

<1  ‘ ; 3 _• ••’ 


"■  \ .1  i/ L^oo  bv'i 

- . i ;.  ' .'j  X »f  lO  *•  ' 

■c'.  . r'XLft 

' ; ■•  * ‘’X 

■..‘■'i'.>  or  r_ 

3 ^1/ 

■ ':  M flolti  . • 


* f . 

r 11 


00  s 


rr-*'- 


<3ltf42'Z4: 


* <it«X 

■ i."^  «nv^ 
t'  nooo'-  ! 


: un  :• 


• . i 


< ‘ s4f  . 

• vt^ 

■V  » .s?r.*rr  * 

■ .i>  ,'. 

t.lv  .,•:  •»  , 


• -^  v o^f 

■v>.n  • 'j 
©’■  .■  -J 


1'  '* 


y .V 


' ‘ J J l^t' 

..o  f i \ S**:" 


^ -■■£  • i 

••  • •■)  . 


j 


1 


I 

i 


'f 

ti 


ACKN0WLEDGEl'i3)HT 


Mr.  H.  F.  Yancey,  Assistant  Chemist,  U.  S.  Bureau  of 
Mines,  did  the  analytical  work  connected  v/ith  this  study  and  work- 
ed with  the  writer  on  the  experiments  conducted  in  the  field  and  in 
the  laboratory.  Professor  H.  H.  Stoek  of  the  Department  of  Mining 
Engineering  of  the  University  of  Illinois,  contributed  valuable 
suggestions  in  the  prosecution  of  the  experimental  work  and  the  ar- 
rangement of  the  ra.anuscript.  Mr.  E,  A,  Holbrook,  Assistant  Direct- 
or, and  Mr.  George  S.  Rice,  Chief  Mining  Engineer  of  the  U.  S.  Bu- 
reau of  Mines,  made  many  helpful  suggestions.  To  all  these  grate- 
ful acknowledgement  is  made. 


.>  \ 


V 


‘X 


s 


\M 


h 

f 


'v  . ' 4 ^ ■ ' A < i. 


K 


it 


. : 'rariiiir 

oj”.' 


t 


\ 


< 


J 


_j 


J 


12 


A STUDY  OP  BITUlkTINOUS  COAL  WASHING  METHODS 


CHAPTER  I 
INTRODUCTION 

The  Objects  of  Coal  Washing*  The  practice  of  washing 
coal  to  separate  it  from  the  inert  mineral  matter  which  is  found 
associated  with  it  when  mined,,  constitutes  an  industry  which  is 
receiving  more  and  more  attention  as  the  necessity  for  utilizing 
the  deposits  of  lower  grade  coal  becomes  more  apparent* 

Briefly  stated  the  objects  accomplished  by  coal  washing 
are  the  concentration  of  the  combustible  matter  by  the  removal  of 
particles  of  heavy  ash-forming  minerals  such  as  shale  and  slate; 
and  the  removal  of  a part  of  the  sulfur  and  phosphorus  which, are 
detrimental  in  the  use  of  the  coal  for  metallurgical  coke* 

These  objects  are  accomplished  by  taking  advantage  of 
the  fact  that  when  particles  of  varying  densities  are  agitated  to- 
gether in  water  they  stratify  arranging  themselves  according  to 
their  respective  specific  gravities  with  the  heaviest  particles  at 
the  bottom  and  the  lightest  at  the  top*  Shale  and  slate  being 
higher  in  specific  gravity  than  coal  jnay  be  separated  from  it  in 
this  manner*  The  equipment  used  consists  largely  of  machines  and 
appliances  developed  in  the  ore  mining  industry  for  the  separation 
of  ores  from  the  barren  rock  mined  with  them*  Ore  concentration 
and  coal  washing  depend  upon  the  same  principles  and  are  similar 


Jti' 

h r M 
rv.  .i 
ro 

n. 


V 

4"  t 

I HSTlAHt) 

* *:5> 

#1.-  , ^.r  1 '"  » T 

■.  -:.  . >zS^V  ItS^  '.^I'/L  c T 

.:  -.ol-'  v.^.-.r  l./.r.tL  Ji^ni  «rti  •at':'*.  Ji  r,’ ' v4?  : ■ 

. :.;■-  '.  z\r' ■''X  .u:-  aiv*.;  :J~r.<. , , ;l«  ; '■' 4'  . , :i  i?r  i*  ■,.•  i,  :ija 

i :;i  . -'a  ir bi.  >.*  rtoi.c  •^:  (^lOC  'V  ..  •■  ...:  iviy,<'l 


t jT'. -L,  •»  •':*  ',  '.  l'».^r  ' iJ-  w ■'*:  . ' ‘li/  uCxJ  :;?  .i00ii^3  a'i< 

r’l.i  M rj.  .i.t.;  aji  .r'/£i  ai '.t  'i, , ;7^n(Iitr:L“-  .i^  ’to  4i  r^',; 

^ i ' f.  jiu;  'll*  'h.  et'J  *io  ;q  “5r,  _i,jsy!  •. 

; 1 Xo:cr'  To  «r': 

^ *r^7i)jx  V ’’  .'''Sriiicjino'o  . 3*i  . ^ -? 

6^  ••  iwic.-Jc-Vi  V,-  ■‘i'3  1. :;i>'iv,  +i  ‘ / .^*.  .. 

/'  '■..  i '•*:  ; t.v  iyr;vXc*u':.-j..  ■ ;,:;t?:..i::'--';  4 \-'4  1 nl  tUltfJf':; 

-■--T:  .:  =.  • riitv  l oi  ilx>aqv  ^ oc-<io5^ 4 -lipiH 

• '-  4.-  '--;:.4  G^-^.  !.:,  • C.-J  Cf-.  -^i-J  t-r:.-  j'oJ  <6r.J 

1 

..yr ; a •!■  su  tJBjj  X»C3  ha.  J‘  xikvxiy  o.'iisfli  ■' 


t?! 


t 

i 


L . 


'o  .fu.  it  X ■' * f i '- 


J rifjj 


, I •«  . 


■ >jiCT 


tC 


■ V .*  I '.  7>.  i 'r£i  ',1  ■ ir;ii,\  o'rt:  orf«  c^i  S\qoXsv  >^  ■.•j;;,'jjiii 

> 


L J I. 

’ • •'  I •• 


- ;-t.. 


i?  iU_iv  x r '*it  sq'io  'to 

6liS  dx><.i-J  ;-  t»qt^  V !j,.’ Xri;;  i:(" 


4jl ' 


15 


■ 

operations  with  the  exception  that  whereas  in  ore  dressing  the  val- 
uable concentrate  usually  constitutes  the  heaviest  and  least  bulky 
product,  in  coal  washing  it  is  the  lighter  and  bulkier  material 
which  is  saved  and  the  heavy  concentrate  is  the  refuse  discarded. 

The  development  of  the  coal  washing  industry  in  America 
has  been  very  largely  in  the  hands  of  the  iron  and  steel  manufac- 
turing companies,  who  have  acquired  coal  lands  and  mined  and  wash- 
ed the  coal  in  order  to  assure  themselves  of  a supply  of  low  sul- 
fur coal  suitable  for  the  manufacture  of  metallurgical  coke.  Some 
of  the  coal  mining  companies,  which  produce  coal  for  the  market, 
have  followed  this  lead  and  installed  washeries  in  order  to  pro- 
duce a more  marketable  coal. 

2.  Advan tages  of  Pro ducing  Clean  Coal.  The  sole  purpose 
of  the  coal  mine  operator  being  to  make  a profit  by  his  operations, 
and  the  amount  of  this  profit  depending  as  it  does  very  largely  up- 
on his  output  and  the  price  which  he  receives  for  his  coal,  it  is 
obvious  that  any  method  of  preparation  which  will  give  him  a de- 
cided advantage  in  a competitive  market  or  which  will  enable  him 
to  sell  his  product  at  a premium  should  be  of  great  value.  By  op- 
erating a washery  both  of  these  advantages  may  be  acquired.  A 
cleaner,  better  looking,  more  salable  coal  will  be  produced,  which 
may  make  possible  the  operation  of  the  mine  when  others  in  the 
same  field  may  be  idle  for  lack  of  orders. 

Small  unwashed  coal,  the  market  for  which  is  practically 
limited  to  the  operators  of  large  power  plants  equipped  with  chain 
grate  stokers,  becomes,  after  washing,  readily  salable  as  domestic, 
coking  or  steam  coal.  At  one  mine  in  the  Williamson  County  field 
where  a washery  is  operated^ practically  all  the  production  of  three 




z -.sae  -ir- M.- 


•-  -W-  't  .liSsrs*' 


>7!ic- 


*'y  T-4 


' r 


' ■ •■•*  ^!u.'!.  J i’jf 

J h.  , >:  .:  >0510^  -J 

■ •'■"  ‘t-’^  ..  • ' -^il  U/'J  cjj  Jti  ;{f3,  :-  j 


if 


: 0 n o ^ '.''  *-•  u 


C‘ 


r»tJw  rtiv^  ..r  .t^ric-  .•  \.Vr.«  : Jb;-  ^CT-.  .:;!  .-r 


-'ri.'c-,  A :.i  V-::  - r'.  rw  X ■-  IJ-  io  ^ ^ ailT 


• V • r *1 


' » ^ f. 


o.  J :c  0 'J  X \.icv  n»»(f  e.*; 

sr  •■•.■.1  '«r:lK  ...«  Hi  r I<-9  'ni  ; ;u  .oo  at»R  . | 

t;  Iv  :■  ■-  „,-  .J.  ,,  , o.* 

*.  yo  : i, : .-(j 

t . . ^-^  «...  1 X-  - o _,"•  '<  ^ r::3<jiaj.’io  ; 


1! 


-O  tJlJir.  fU'  t rto'i  -’>X,r  J L :.  f.  It 

r^:lv  X^w:}  Ik  *! 


oj  T . 


* • '■  ■ 1 1..<  j.-.J  >caeX  iK,r- 


.■-l-'  oil-' 


.'  f . 


t ®v:j.K  |i 

ri 

ol  'x^Tf  5?‘r,c.-  c r;:..  ■ S( 


ft 


#ntrr(,  .'  ; ris,.  ■1.,.;^  :.,,i  x . ■.  «.v  la  ii 


!i 


^ ' ' - , %»  A i.  ^ VI'  X ^ X I iX.  f ^ ^ 


'■CO  r. Xci  'r  I ;t 


<• 

■'  x^cirl'f  o&X‘A<}  0,' J o .' / 1 vJ  ..•<,' .f' wo  '.‘X  n-^-  i* 


• X.';  £>’••: 


.' I'lrv  — -xrj  "Xo  ':'oj,{v,» 'ii'!  v^rrj,  ♦■..tj  r-.roJ. r-i" <*. 


..ar  r.Xrtr  J;  r--s.r  -»vj- ' IX  ■ f.i;00  '.c  .'■.;-  -.-  -X -.;v6...  -j 

V.  .jur.  v J ■>.  0 . !i;cf"  .-uins-;;:  .-  J=  :-J-  i-,  oX  f* 

* ' '■**  V-"  '"».:J  Ijp  i • J 

* - - ‘v.T'T  D.7__r.'i'r  X«oo  ? JW/..  . :.".n'../  ,•  '.t-lOvX  io.tv'«''  , :j  v.r.o  !| 


ni 


■'  i Xo  ■;  .•  e..  }•  aon 


Uy  ^'o: 


* 'irj'xo  lo  'XOi  X - o r .-^ai  • 


•f  0 iiq  ^o.i  -xol  i,r*  '.r-oo  fa- fw; -.i;;  XXn:?C 


►.  y< 


,y  [o  •■Cj>  fa*v  - K'Juu.tq  o;.*TjcX  ::-roic'i?);qc"?rx^  cX  i)  ' i l£ 

I 


I 


* t ' ' 


C:  ' 1 


■ ««  X. 


, .ti^ti.'.-v  tvX'-!  ; , 


...  . ” ' • ■^i''  ■.'• 

ci  O.-.Xf'i  Oi.o  w^/.  . irc-'j-'x' 10  ' i.>fC'0 


X, 


.^-  iu  /i. 90X  IX  1 •••iscro  4I  „■  ^ 


* ^ .i* 


14 


inch  screenings  with  the  exception  of  the  No,  5 washed  coal, 
size,  is  sold  for  other  purposes  than  steeun  raising.  The  number  1 
nut  is  sold  as  domestic  coal,  the  larger  part  of  it  being 

used  for  heating  Chicago  apartment  houses.  The  No.  2^  , 3 and  4 
sizes  are  used  for  by-product  coking,  cement  burning  and  for  domes- 
tic coal. 

In  some  cases  the  use  of  a coal  washer  makes  possible  the 
profitable  operation  of  a mine  in  coal  which  without  some  method  of 
cleaning  could  not  be  marketed.  This  is  the  case  in  some  of  the 
isolated  districts  in  the  west  where  the  hi^  transportation  charge 
on  outside  coal  gives  the  local  operator  a sufficient  margin  to  cov- 
er the  cost  of  a quite  elaborate  system  of  preparation.  The  coals 
of  Montana  and  Washington  are  largely  of  the  type  which  must  be 
treated  by  some  cleaning  process  before  they  can  be  used.  Tiie 
Alaskan  coals  also  occur  interbedded  with  shale  and  slate  in  such  a 
manner  that  the  coal  as  a rule  cannot  be  mined  clean  enou^  to  use 
in  the  raw  state. 

While  as  a rule  contracts  covering  the  sale  of  coal  on 
specification  provide  for  the  payment  of  a premium,  often  two  cents 
per  ton,  for  each  unit  of  reduction  in  the  percentages  of  ash  below 
the  amount  specified  as  allowable,  this  premium  is  generally  not 
sufficient  to  make  washing  profitable.  At  present  the  possibility 
of  securing  a higher  price  for  coal  after  washing  depends  very 
largely  upon  finding  a market  for  it  in  those  industries,  such  as 
steel  manufacture,  by-product  coking,  gas  making  and  the  ceramic 

^In  Illinois  the  following  sizes  for  washed  coal  have 
been  generally  adopted  as  standard:  No.  1,  2"-3”;  No.  2,  l'‘-2” ; No. 

3,  i«-l«;  No.  4,  No.  5, 


I. 


\ 


^ I ..  I-'-'.  . ..v.^::'+  uq':;,-';  •I'jriJo  10"  ';■  A 

^•.■..:.^'-J  .‘i  ?0  '■.-.''.-aI  ®.,J’  , ;c*’  oij,'.'.  tcN  .'-i  bJ.OA  - * :.  ) J j.; 


t ^ ^ . . ' .1 . 

' ' c'  . . X '1  . ;q>.  I :ff.>  vr'iv  • -t  _ brp;; 


T‘i  :•  L . Jn 


' .’ V o J o : jOZ  ■ - ' b *. 


s»i  ::i5f;oc/  t^aataa  tiOAi*Air  Xijjn 
•> 


. -^^^0  oi  J 

> tux^  z.ot<  •:■  ?:'0C  ft* 

•.  , ;•.;  -nt  . 'to  • :.t.  1 J 01  o^ilr^q 

i.  f»:'r  lo  or.*:*)  rvi  '.r^*o  s.-.,  .- : -i.lf.'”  . , ♦»  ■:  r:  !?.•  .‘cu  cluoo  srlftr.eXD 

T.ir''  r: . I ■'  ..:  O.  ^ \\^  j -rr  .Z;  o;*! 

00’  1“  *'i  ’^‘1.  ' :.'tj  aJ  *t  X *X^qi'  r.r;iL  •;{!  unVlJj  i.  >C0  OifX'jJi.'C  .'lH 

' wi  ’.'.  . ■,  •*  ’ • io  riT-:»j' - rJ«i\ jo’-atf-  0 'X^,. 


I.  ’■<y":  iicliCw  0<TX:J  t;.  - . /io:  -.  .J  o-* ..  :c^-  .'i.*'  '*  r"  4/..  ,+  noji!  lo 


• V 


i- 


■ ■If  i,-’^-.j  y,o'J:^el  »r*-.5>o  .‘t- - •^;:^r  •*,1;)  ort);}  vc 


1 


?aw  .::lf/  X “li'j  .jJt  tL':;:fC  oniA  . co  \ 


<*"■<  oj  "'liL:  AC' 


A / 


•jL  t "/*  5 »*.  X •'  - ■ r s : : ■r'J  *X  r.  n; 

. • **  9tii  hi 


I 


nc  Xaoo  'r  : -Z»e  '^rt^h\'oo  8.  • ■ -aXv'i  jj  . .t  ^ 


n*)j  V-  , - '•  ‘ ^ -j  ■ V.  ; ' tJ^i*  'f  x * a : -^  r 

■ .‘j 

vclc-  ;.;j  iO  (.►C'|jai.':ori»q  ni  lai-pT  *to  w^irt-j  Knxi*  ':•.*  , 


I ••-C-'  -i  . ;jLnvfjir/i  n£  J ./c-.-x  dd. 


*::t  f ' ---  - ' :^nocr<£_  .ir^;:  . a $.X..-  03  ^s,^lxit'tiun 

\1-3V  V 'V  'i  j'i.  I<iCO  -IC":  ociaq  'iS>^’T.Xd  Li  X 'lo 

■ ' ■ 

£i.i  jfoxTf^  , ? -.v,*  f^;.  ^ - 2 ■ *: bl- i.  ;;ni  .2  £ ^-.c  ■. 

>i'n. ':mo  s.',  ja;.,  :' i jji.;-'  C5a>*;^  ,^q}>Jar'  Jyi'.ci  ~v-  ^ ,xj- C'.-'ti.f'tn*  .'.'•''.is 


* li'  : j;  ^ • ,o5!  ; 'v:-»'  ^ 


-■.  l«rAf  ”?iC''i’I  I [•■'■ 

; '_ . , ■ 7 ■ ‘ ' '/h  ■ ' ' I.  X . 


, . . - 4 


j.  . t < 

< * • • { 


f"  T. 


H 

-!i 


15 


• industries  which  require  a low  sulfur  and  low  ash  coal* 

That  these  industries  will,  in  the  future,  have  to  draw 
part  of  their  supply  from  fields  outside  the  present  restricted 
areas  of  production  of  low  sulfur  coal  in  West  Virginia,  Kentucky 
and  Pennsylvania  is  becoming  obvious.  While  our  reserves  of  coal, 
which  like  that  from  the  Connelsville  district,  can  be  made  into 
good  metallurgical  coke  without  washing  are  by  no  means  nearing  ex- 
haustion, the  big  consumers  of  low  sulfur  coal  cannot  provide  for 
their  future  needs  by  extending  their  holdings  of  coal  land  in 
' these  fields.  Furthermore,  their  rate  of  production  has  about 
reached  the  peak,  and  cannot  be  expected  to  keep  pace  with  the  in- 
creased consumption  of  low  sulfur  coal  in  the  metallurgical  indus- 
tries. The  deficiency  will  have  to  be  made  up  by  the  use  of  wash- 
ed coal  from  other  districts  where  inferior  coal  is  produced. 

The  rapid  growth  of  the  by-pro due t^  coking  industry,  as 
distinct  from  the  iron  and  steel  business,  for  the  production  of 
coal  gas  and  fuel  coke  for  the  market  furnishes  an  entirely  new 
market  for  washed  coal  from  the  desirable  coal/  seams  of  poorer 
quality.  For  this  purpose  a coal  is  not  generally  subject  to  as 
strict  requirements  with  regard  to  sulfur  and  ash  content  as  a coal 
to  be  used  for  metallurgical  coke.  The  limit  for  sulfur  is  common- 
ly placed  at  one  and  one-half  to  two  per  cent. 

That  the  production  and  use  of  cleaner  coal  for  all  pur- 
poses would  result  in  a great  saving  to  the  industries  of  the  na- 
tion goes  without  saying,  but  the  coal  mine  operator  cannot  be  ex- 

^In  1920,  for  the  first  time,  the  production  of  by-pro- 
duct coke  in  the  United  States  exceeded  the  production  of  bee-hive 
coke. 


f « 


% 


'•m  

”i 

M } 


x'ir  f 


I t.  r.  ^i ..  4.  ,.i  t/o'''*"  **•  . . ■ ,. , 

-"-  > • -.i?4>;|r  f»'  ar?i  !' 

f- ' * I ' SiLfb  ‘r  .1  '*  -';  j ^ ^ ■ Cj 

•■V.  • -J 


'.'.i  t\- 

' ' • i • ' j \i  j . c 

» ; ;:t.:iiOO  . •.:  'io  ;•- 

• !*'C  t.:o  i 1 


r^^uJiVc  •;^-i  ♦ 


Bft©** 


l7Cfc  fc''" 


-•-J.:  ; 


*•  ■ 1; 

■ .'  - J l'-.  :o0  ©rf?  '•  i.-'i*'.  i&r:  . • 

^ . ' r ■ ■ •< 

• -‘■’‘■J  . . V"’  .'  ^rfE*'-"  ^-  - <■  . • •/•  f 1 J 

^ ^ ‘ ' ' +^  '’X>'r..C:  X;:i 

^ tonrr^n  .:  r.  ^.-:-;r  t..X  ^ ^ ^ _ | 

^ ‘'■•■■f.  £.  :c.  : iTjr.tio^  ^-:>•^  | 

; ryb,  ms'.r  nci.-.utic'zrr  : :-  ^ -.n  ^ '! 

“ ■ ' ,t 

V ' • ri 

- - .--T'  00/-  :•  o I 0^  y??v:oc^9  Jofui^b  e*: 


~ 


t 8 ‘ bc.'oy.e’i 


f; 


r 

■ •X-i;H  !,<:•  , ,i  T:^aj  :jX  , i-jix«dira04.0  j! 

•'“'  ‘ '^''  • •■•'  ^''•- ' XX i"’/ . • o :»v.l . x'l . .I'l^ 


. ' -•.  -i  Axco  -rr^-^Vt*  ;-ri:%,vv  xXox-Ui,xi,  0 i : -i , X>.,,a  ;jo 


, -. . o.-io.njo 


'<•'■  -/ 


o -{^vEr.*x-_  oioo  :•  or^r 


■r 


lo  . K o . . cxq  o.  .’  'X.  , ifriiii^oi  !*<•>,>  e';io  iim  i - --rt  ^ T j :!  ^ L ^,,4 j 

^-,.  ;j.;  ^ 

'-X?  ■ ,ol3,o'ii jj  J CiCl't  IroTv  b^i'.D^  icl  * OA^^.;'n 

- XD9;,:},.';  \Lt  - '.i^  j :ri  a:  I.  i-o  - o'ioo  t.fr  . ^j-iX /i/i'  : 

^5  X:-._suc  hr.^  TJmua  c o- o*:  ; *,  f.J  irr  rJoa  ' 

‘ ■ " ‘**'*^f ■•'•'  «.j  . ■•?«•'■  ^ i,  ttjre,-T  ‘tv* 


,.*:i:>0 


, f 


«.  r ; 


•''«  ‘ ~ ■-<  ;>tio  Jo  ■ 


' i9^JsrXo  't^  - ■■  ..,  . nc/joj.ff)oi-4  ^ ,j  >••  ^,-j 

I*  - oJ  r^roir^a  Xlooe-:  Mxfg-  ;.p^  j 

. X J.;rx30  ./lo^h'icoi-  ;io  ixioc  .©/fX  4.-V  . i -/  :.  j u(.  :j  - : e^OT.  • boi  J 

■{  • * - 


-O'U.*.  - 1-:  n4;iJ.>;H.o 


• ■ - . ■ 0*1 ; ..  , i.‘  .7,nj  'io'i  , 'xr'Pf  rri'X 

**•■  X ooLoaov© -iJ  ri  ^ t<vi> 


• • . i*  • 

.•7  ..  M. 


.Jipllr'z 


16 


pected  to  supply  washed  coal  to  the  market  unless  it  commands  a 
sufficiently  higher  price  to  pay  the  additional  cost  of  the  washing 
operation.  A demand  from  the  users  of  coal  for  a cleaner  product 
and  a willingness  to  pay  for  the  increased  value  received  will  make 
possible  the  washing  of  coal  for  fuel. 

The  two  chief  advantages  to  the  operator  of  producing 
washed  coal  are  a wider  and  more  dependable  market  for  his  coal  and 
a higher  selling  price.  These  two  advantages  are  being  accentuated 
as  the  users  of  coal  realize  more  fully  the  advantages  of  using 
clean  coal  and  the  great  losses  due  to  handling  the  worthless  dirt 
in  raw  coal  thru  the  cycle  of  production,  transportation  and  utili- 
zation. 

3.  Advan tages  of  Using  Clean  Coal.  The  importance  of 
this  subject  of  clean  coal  will  vary  more  or  less  with  the  widely 
different  uses  to  which  it  is  put.  In  certain  manufacturing  pro- 
cesses where  the  coal  or  some  of  the  products  derived  from  it  enter 
into  the  composition  of  materials, which  would  be  damaged  by  the  ad- 
dition of  sulfur  or  phosphorus,  the  use  of  clean  coal  is  mandatory. 
The  principal  industries  which  require  low  sulfur  coal  are  iron  and 
steel  manufacture,  gas  manufacture,  the  ceramic  industries,  the 
smelting  of  ores  and  the  heat  treatment  of  metals. 

On  the  other  hand,  to  the  great  majority  of  consumers  who 
use  coal  for  fuel,  the  advantage  of  the  use  of  washed  coal  is  sim- 
ply a matter  of  dollars  and  cents.  It  is  impossible  to  discuss 
fully  the  application  of  the  problem  of  dirt  in  all  the  varied  uses 
to  which  coal  is  put,  but  two  typical  cases  representative  of  the 
two  classes  outlined  above  will  show  in  a general  way  the  extent  of 
the  economic  losses  which  are  directly  chargeable  to  excessive  im- 


I 


1' 


* 


r4  • 


Si  \S  ' jl|' 

! 

. 'i, : •Diil'r’iu*  ; 

• * V X9t*  0 

■t  Ciic.'ji.iij:  I’iv  br.  * ' 

W|^4  f!  . 


'.«i.»0  31  ci.  • 'I'M 

u:i:  V.:  1c  30C  ; 

0 Jo  r ‘I c"*  J.  .0  > : 

t>'  -;C  iJj  "'.•’■i  r'^r  •;  . • '-^qI 

- ' . ' '.t;  V ■;  X •?  ,> 

U’i-tJr*;  *. ..  * ' _r>--jivjaev^i;  ioiiu-  cc^  9^ 

bn  I-;c:.:  i-  ■ •'  /t.  , f ;?*rc.  - - 

^.T•  - .V-  ..  - -..sr  : . iflifSli.i.. 

■ .•  = --^<”-  - ' / :>rcu  t>:;i.Xi*^v  j < T«.  ^ • q.  * 

'’.••■  ■ “ ' ' *.  •- ■ • ■•  ■‘-  oj  ■.■.>i  .*  -T,^  fr*J  j-0  o^ri.r 

."j.iAi  _ - ,:>:*ji;.  -X,.  io  re'-*>^  r..  i :- ; 

. ■ , t-*- 

q-'i  V ' , 2X-  Xl‘ 


i 


...  ft  . r Ji*r  “i . o : ,.  i ..y  J.ilw  i:.oo.'r',  .jroi 


" . i-:  o ;*! ni  ;.X 

i rto-r  ' ovj'iob  ..  w 


L- 


“ t. 


<4?ii  'T  j Xoou  >».  c-'is*.  ''.oci-r  £fc>  I 


}' 


-J  ••  A 


. •.  , j. .- 1*1 0 : H„fT  ic  :t  iJ 3.. ..  :c 0 . o. IJ  ; j r. j « 


If 

1-r, ' 


• ^ soo  nsoS, 0 to  fti  -X  J-  , ■'. > "i  rvrtc^  to  f. •>  f s 

>.;.'  .T(-r.  '>1:  '■  ■CO  •:•'■;,-  -cl  o-xiio  o-:  ^-.  r^/{T 


s 


li 


^i/'i 


> :j  . -.4.  t ^ , ..^Xoalx; - , 'i:;- • ,- 


I;  r,  e ” 


- • • ‘ ..  ‘ 3(%9ft-:  ri-Ll  * ^ J ^ .'  -.  • a *’ 

» ■'  w 4 • . 1.. 

1--V  ..  ^ <..w«««.a  • . fillet  ...  J .,;-r  »r-j  «.  , , ' 

/» 

- ’.  j:  I«oi»  i)srie/iv  -Vo  aajj.an’.  .:v  - . < vo.^  sr'-^  -iwl  8-'/  f 

^ ■jMSJi^aX:  Oi  ;»J  yianC-pTi  el  J ; j./: . a'SAUo»>  ::  ^ i .;!?  o -Iq  I 


iOf:/.  joi-X.^iV  1.!  • -i  J^lb  lo  C5^^ul4  •4  1r.  XK-f^-Xio; : 4 , - J fa 

1- 


'».n  'Io  ovi.^r.jj— .'  'f.v''-:  i.r.B..0  lx:*  Cro-  ■ oj 


c J 


• -*  • X T 'uto;-,  -j  :ii  wo.'lB  .Cii  - Jbo.T. 


■ ' y /-■  > r 4, 


o c.'  ftl 44 !>x*X3rio  ftXi  .‘■'rXd-i'  ; :.i.-'^o.:o.'3a  o^ilvS 


3 


17 


purities  in  coal, 

V/ASHED  COAL  FOR  COKING 

For  the  manufacture  of  metallurgical  coke,  particularly 
if  it  is  used  in  iron  and  steel  making, a low  sulfur  coal  producing 
a coke  of  about  1. 10  per  cent  sulfur  or  less  is  required. 

Some  of  the  Eastern  coking  coals,  such  as  the  Connels- 
ville  and  the  Elkhorn,  come  well  below  this  limit  in  the  raw  state, 
but  with  many  other  coals  which  posses  good  coking  qualities  v^ash- 
ing  is  necessary  in  order  to  reduce  the  sulfur  content  to  this 
figure.  In  the  southern  and  western  fields  most  of  the  coal  used 
for  coking,  though  low  enough  in  sulfur,  must  be  washed  because  of 
excessive  ash. 

In  regard  to  the  use  of  washed  coal  for  coking  Wagner^ 
says,  “It  is  an  unquestionable  fact  that  coal  washing  will  greatly 
assist  in  producing  a high  grade  coke,  as  even  a comparatively  low 
ash  coal  will  occasionally  run  high  in  ash  and  possibly  sulfur,  due 
to  careless  mining  or  to  the  irregularity  of  the  coal  seam,  the 
washing  insuring  a more  uniform  quality  of  coke”.  An  example  from 
actual  practice  will  best  show  the  relative  advantages  of  washed 
coal  and  raw  coal  for  making  metallurgical  coke.  The  following 
figures  are  taken  from  a report^  on  results  secured  at  the  plant 
of  the  Nova  Scotia  Steel  Company. 

^Coal  and  coke  p,  104. 

^W.  H.  Graham  Trans.  Canadian  Min.  Inst.  1918  - 231. 


18 


TABLE  I 

Coke  From  Raw  and  Washed  Coals,  Nova  Scotia  Steel  Company 


}^aw 

slack 

Coke  from 
raw  slack 

Washed 

slack 

Coke  from 
washed  slack 

Coke  yield  per  cent 

64.  5 

62.0 

Volatile  per  cent 

35.0 

38.0 

Fixed  carbon  per  cent 

53.0 

81.  5 

58.0 

93.0 

Ash  per  cent 

12.0 

18.  5 

4.0 

6.6 

Sulfur  per  cent 

2.0 

1.2 

Since  the  heating  value  of  coke  varies  with  the  carbon 
content,  this  shows  an  increase  of  14  per  cent  in  calorific  value 
of  coke  from  washed  coal  as  compared  with  coke  made  from  the  un- 
washed coal.  The  washed  coal  also  contains  8.5  per  cent  more  vola- 
tile than  the  raw  coal  and  will  therefore  produce  an  8.5  per  cent 
larger  volume  of  gas,  neglecting  the  amount  of  gas  occluded  in  the 
coke.  The  washed  coal  de-ashed  to  the  extent  shown  above  produced 
4 per  cent  less  coke.  These  advantages  lead  to  a further  advan- 
tage in  increased  oven  capacity,  in  weight  of  actual  coal  coked, 
volume  of  gas  produced,  and  effective  carbon  in  the  coke  produced. 

The  decreased  capacity  of  equipment  and  the  increased 
cost  of  handling  throughout  the  cycle  of  operations  due  to  the  use 
of  coal  containing  an  excessive  amount  of  worthless  ash  forming 
minerals  is  apparent  to  all,  and  the  losses  accruing  in  actual  op- 
eration are  usually  greater  than  the  theoretical  calculations  in- 
dicate. 

In  the  blast  furnace  a ton  of  coke  from  v/ashed  coal 
gives  230  pounds  more  available  carbon  and  24  pounds  less  ash  to  be 
slagged  than  a ton^  of  coke  from  unwashed  coal.  Thus  a smaller  a- 
mount  of  fuel  is  needed  to  maintciin  tl'.e  required  temperature  and  a 
smfiller  amount  of  Ime  is  needed  to  slag  off  the  impurities  in  the 


• Ir 


I 


■ i ■ . ‘ ■ ■ 

•< 


J 1 .V 


I 


4. 


*) 


L 


h 

' ' ■ '.L 


■j..  :•>  .7 


- . -i^q  i>  t' 


- ' • . ■■  . f 

t ■ .. 


t 


■t 


■ ') 


) ) 


l'J 


< 


5 


#-> ' 


) V 


I ■• 


’ ; j 


> 


i 


r» 


X 


A. 


X 


J 


:.f  . TJ:-" 


/ 


:; ..  -L' 


.'I  ■:> 


f 

i 


■'  rc-'^  oi 


■( 


r 


I 


r ■ 


j 


) 


..  o 


■1  o:^  ’.'I 


r * 


j 1..  •; 

>-■ 


J 


19 


coal.  For  this  reason  a much  larger  amount  of  ore  can  he  charged. 

Perhaps  the  greatest  value  of  the  washing  process  as  ap- 
plied to  coking  coals  lies  in  the  production  of  a coke  of  more 
uniform  ash  and  sulfur  content.  It  is  possible  to  produce  good 
pig  iron  from  high  sulfur  coke  if  the  ri^it  conditions  can  be  main- 
tained in  the  furnace,  but  temperature  control,  always  a difficult 
thing  in  blast  furnace  operation,  is  impossible  with  coke  of  irreg- 
ular composition. 

For  instance  if  the  charge  is  calculated  on  the  basis  of 
1.20  per  cent  sulfur  and  5,00  per  cent  ash  in  the  coke  and  a batch 
of  coke  containing  1,60  per  cent  sulfur  and  10.0  per  cent  ash  goes 
in,  as  soon  as  this  coke  of  lower  calorific  value  reaches  the  re- 
duction zone  of  the  furnace,  the  chemice.1  reactions  are  arrested, 
the  silicon  goes  down,  slagging  of  the  sulfur  is  arrested  and  a __ 
cold  furnace  producing  high  sulfur  white  iron  is  the  result. 

On  the  other  hand  if  Uie  charge  is  figured  for  coke  of 
1.6  per  cent  sulfur  and  10  per  cent  ash  with  the  ri^t  proportion 
of  lime  to  flux  and  absorb  these  impurities,  and  a charge  of  good 
coke  goes  in,  the  furnace  gets  too  hot,  the  chemical  reactions  are 
intensified  and  an  iron  too  high  in  silicon  for  the  basic  process 
is  produced.  These  dif ficulities  cause  a great  reduction  in  ca- 
pacity of  the  furnaces  and  a bad  slag  as  well  as  impure  iron. 

Grfihem  in  discussing  the  effect  of  hi^  ash  in  the  coke  says,  •’In 
a furnace  producing  No.  1 basic  iron,  the  loss  of  iron  in  the  slag 
increases  from  1.0  per  cent  to  8 or  10  per  cent  in  a cold  furnace**. 

WASHED  COAL  FOR  FUEL 

Primarily,  of  course,  the  increase  in  fuel  value  of  a 
coal  due  to  washing  consists  in  the  increased  proportion  of  valuable 


.•o^j  ri-ju.XL  » 


iir 


; ?90  ..>ox-T  t 


> ^ ri/^  - ■»•■•..'  *>*17:  S(!l ! 


:>•■.. >0  rj  o^o^  . ic  t'lv.ro''  . i.  usil  aX^Lor  t ' <>111 

b ;oj^  nr.'f'' tvK  )Xii?coq  j ' , -xir'i*  . . . ,n  . •,  iriollni' 

;rt  ;!-0  — ^T  Li  ojLdo  A . - . ac-xl^^lfr 

1 ,^^^•  i : r .'M  1 , ■..1 4;  ^ .^-rA  o jnij/l  %'^A  Hi  ror*’ 

■:  -.'.Ti  ?:  • '3  v-v  <^X  ' i <>60^113  1 , vw"*  lO;^©  7'  ij  J .llxi? 

^ . lllooi^oa  1>X« 


L-': 


f 


, _■  :-'  4 c' 


nc 

: ■"  " 0 

1 

•■‘X 

•♦3‘If  '‘C  'B. 

t 1 1 'r L loil 

b.  w , -x 

' • 

; ; 

0 0 

' “‘V* 

.y-.,-  •cajj'j;,  jb:;j  ir»f'CS.I 

la  >a  'i 

. •'-7 

iC.'H  » * i‘.tl '.laoa  d^Pd.'xc 

• b'-aioOV  •■•  .’I 

•V  •.  i r j 

•t  X 

l>f»  'XO  vol 

1'..  '»!!■!  i;y  iJ  s*v  bv  oe  , *»1 

* i / i 

• ' i 1. 

>Xr' 

|4>  If^  /•• 

'•  'oiLz  ^0  esos  m>iJot/b 

; :•!  a ai'i  A -.t 

'Ui'i  U;  :- 

-N  ’ j 

-■  'to  gni 

r '’oo».  iWdi  ‘ 1 

J 9X1  ai 

no'ii 

•:u"i  1 8 

ri^Xrf  ^asaxr.a  iXOw 

■>  “ 

■-•  ■ . . j '■*  *•.  1 ^ 

: a. 

0 a ■ u 

>n:  .'l  1 .:io  i'.'J'  !iO: 

I 


iTci^  i (i-Xj-C  ’ J.'  ..-  •.*  .-'.‘ir  ‘iQ-,  .fn90  i^q  jX  ^-.v.i-  Jaso 


liOGj.'  :r  ':..  -in  - ;•,..  , ' . '.^  i iicoi  fri  X^ri  j ?::,'C'l  7tiUI  'ic  i 


::.  oX 'o  :.«*r  ' -jl  rro-^fri  e^^il  ,7  0rt  coj  -ictp  a:;  .ii'iir'i  5'i  ,‘A  oeo‘^  :jXuo 

-■  '*^ 

-•.i-.'«-:c-r:  ::1;;.;,J  g,/4  .JQ-J  n .'IXliJ  rtl  ooi  aTi  j.-a  5)Cr^^i;'  .^lai 


1 


'} 


- -o  ;<1  xxjjs^i"  lib  a-a.  ? .^.'^ouaO'iq  s^i  f! 

• J 

■ T t; 

. 'Tx.  -a/j*:  .1  , ? L’Xow  a-  ilr>  3 tirt«  a ■'Ofixiifi  ‘jAZ  ,y,i Jto^jq  1} 

...  ■ ' ' 

, -3rsi3  c. -.0'.  <-"(.  i '^.,iA  io  9dt  -.i.-)  >iX  ii  iiloTO  jj 

• '.)  .-.i  ;:o-X'  ■•■5  aooX  •■•;.;  , -oil  oic.:..  X .b.:  ^.r.i'':  w'x'i  'bJSaaJ'T  a 
'1  ly  Z bXOO  JB  .;.i.’'^..a3  lOCr  OX  "T.  <.  .<  oi  1 iff  -C  ,L  . ' . '■  ’0‘15^'i 


7^', -»■•  I /-■.•,  T/  ■ r\  r--r-  ri  ■ 

' . .- ' ■ . I.'  • LI ^<J  \ . I . .Ji 


^srr  X-'jX  t.^  1=:.  ,-er:jorj  i 


Dli.a-, 


iV  i accj^cqOiX  i)  J baa'ic  -.X  ai'f.t  ai  sJf^XK.;co  anl;Xs/jr  o, 

’ ■-  — ■ in:iaiS£^.i.-rtr.-4: -S  i-T-  .«r'3Ct‘^srt!lr~ — 'i:?;  . : 


20 


combustible  material  due  to  the  removal  of  excess  ash.  Mr.  Thomas 
J.  Dra.keley^  in  a recent  extensive  investigation  of  the  relation 
of  ash  content  and  the  calorific  value  of  coal,  confirms  the  con- 
clusions of  earlier  authorities  that  for  a given  coal  the  decrease 
in  B.  t.  u.  content  with  increase  in  ash  content  is  practically 
uniform  and  constant.  In  the  average  coal  where  the  dirt  is  chief- 
ly shale  tmd  slate,  the  calorific  value  decreases  about  1.2  per 
cent  for  each  per  cent  of  increase  in  ash  content.  If  this  were 
the  only  disadvantage  of  using  dirty  coal  the  consumer  would  have 
small  grounds  for  demanding  washed  coal,  as  the  difference  in  price 
of  coals  of  different  quality  is  ordinarily  more  than  sufficient  to 
compensate  for  this  decreased  B.  t.  u.  content  due  to  hi^  ash. 
However,  this  constitutes  only  a small  proportion  of  the  total  loss 
chargeable  to  excessive  dirt  in  coal.  The  various  factors  which 
make  up  the  total  cost  of  using  dirty  coal  may  be  classified  under 
three  headings  as  follows; 

1.  Cost  of  handling  worthless  material. 

2.  Effect  of  high  ash  content  on  thermal  efficiency. 

3.  Decrease  in  capacity  of  plant  equipment. 

Since  more  than  half  of  the  bituminous  coal  used  for  fuel 
in  this  country  is  burned  under  boilers  for  the  generation  of  stesm, 
an  analysis  of  these  three  items  of  waste  in  the  use  of  dirty  coal 
for  steam  raising  will  best  represent  the  case.  Losses  in  other 
uses  of  coal  are  similar  but  perhaps  different  in  degree. 

COST  OF  HANDLING  WORTHLESS  MATEIilAL 

The  first  loss  incurred  in  the  use  of  dirty  coal  is  the 

^Calorific  Value  and  Ash  Yield  of  Coal  Samples  From  the 
Same  Seam  T.  I.  M.  £.  Oct.  1918. 


21 


freight  charge  for  the  transportation  of  worthless  material  from 
the  mine  to  the  point  where  consumed.  This  is  a loss  which  accrues 
to  every  user  of  coal  for  any  purpose  unless  his  plant  is  located 
at  the  mine.  Where  the  transportation  charge  amounts  to  as  much 
as  $1. 50  per  ton,  v^ich  is  about  the  present  rate  from  the  Danville 
district  to  Chicago,  the  cost  of  hauling  the  worthless  material  in 
a coal  containing  6 per  cent  of  removable  ash  amounts  to  enough  to 
cover  the  expense  of  cleaning  in  an  efficiently  operated  washery. ^ 

Generally  speaking,  the  Central  District  coals  of  wash- 
able size,  under  three  inches,  contain  at  least  6 per  cent  of  free 
dirt  as  marketed  in  the  raw  state.  This  applies  to  the  average  tv/o 
inch  screenings  ordinarily  used  for  steam  raising  and  probably  a 
large  part  of  the  domestic  coal  of  stove  or  nut  size.  Holbrook^ 
gives  the  average  ash  of  32  samples  of  Illinois  screenings  collect- 
ed from  various  parts  of  the  state  as  17.4  per  cent  with  a minimum 
of  10.1  per  cent  and  a majcimum  of  29.7  per  cent.  Assuming  the  fix- 
ed or  irranovable  ash  at  10  per  cent,  this  indicates  an  average 
free  ash  content  of  7.4  per  cent.  Under  the  extra  cost  of  handling 
may  be  included  in  addition  to  the  increase  in  frei^t  charges,  the 
increased  labor  or  power  required  for  handling  coal  after  it  reach- 
es the  plant,  increased  storage  space  required  if  coal  is  stored, 
and  cost  of  increased  ash  disposal. 

^An  arbitrary  deduction  for  the  moisture  in  washed  coal 
is  commonly  made  by  the  Mining  Co.  in  billing  out  the  coal  and  by 
the  Railway  Company  in  computing  frei^t  bills  this  amounts  to 
from  3 to  15  per  cent  of  the  mine  weight. 

^Dry  Preparation  of  Bituminous  Coal  at  Illinois  Mines, 
Eng.  Exp.  Sta.  Bull.  88. 


I t 


• ' ' •xr:  • 

. Jifunoo  '^f'.-j>rf».-  t* 

.>.*-*^••01  11  Jr.  -.j  r.i,i  i,-i5f!aLf  DHu  i.y;  ic'i  I-.o::;  - -j  o.‘ 

■ ««  o.T  ( nfr> j ; ^ ^.-XT.aw  . ^■.i 

1*^'  Civ.ii"!‘.i  .' ' ' -T  rrf.'xl  *,i'’  i ■ * r*'*’’  ,, 

r i ,.1  i , . ...  ^ .i 

l-i-'?..,.'.  C,inow  to  >««0  e , ■ ratrfo  e; 

■-■  •-'  on.  ;c  i-  .ni-  ...  f .u,-,-  .j.,  ...93  t..,,  :■  X.  J ,, 

: t ■ 1 :j  .t  aoa»(|^cd  ariif  toroo 

.1  Bfcnf!  ”'  * ■ 

“■*  • - V...  r:  .••<’':>  , *Xt:i  . ( v.jIT  .'tv'i-Tjf;) 


tj  Vw 


’'  /.r  .,'.1  Tjt.  .rjv  3 ^• 


ti 


'T^VtSrL  ‘ 


«a  n£d3 


r U4.I'?  * J JT  .f 


;4X,.  ;^nxi}i  •:  7oT:  ii 

• ** 


UT  'Xiic.'y  Oi  9.,’,';:;  Oftt  . - , 

X.ost'>X 

,» X ‘7‘j , .1  '^c  t-'  j :iaa  T3V 

Tovis 

. 

' ; 

V «ut't  at) 

jisn  TO  avow 

: j o . V,  I X . t ai  on  i X r r '1 . 

i!  i.4.  .'.  '■C'L~'  s^‘.;.'.)  ’X*!.,  '•  . ’‘'J  *■. 

t:  Ou:  v.-;.rrnn3;.  , \t90  i , _ j,  bit^  . , I .OX  1o  . 

I; 

, :!  .J  . ‘ ■•^■»  't {*•■::  Cx  i'  ■.  rt..^-  -jXt'uV'oaH: „:'(i  io  69  ji 

;! 

- T.'-.-  i'jii  .w  ’'^jo  ^- . :o  ^ ' r,?r!oo  'je'il  1, 


I 


.'■■-•■  : - 00  . 'f.*  r?f  .>. 

« ‘'^  .xo-ct  ni  ?'u  ;x  c-  0 • ■ itoXJix»£)J#  aX  ha  ,i , 

-.  '..O'i  vj  I 'las'T.'i  I-..UO  ’xol  *'T“:  ,'..;?©*i.:ifriV'0(t  'rojx  L dua. '.'lani. 

' ''“'r  Xt,oo  “ii  A*%«n  -;  «»;•.  r'.t.'a  |>j>pv;';3i^9ni  ,^nitlq  *>  §.« 

■■  . ‘ '•■-/■^Jab  b'TUiu.di^XKii  X.ic  ■ baa, 

• , 

' !!• 


•J 

i 


l-.:oo  'Ort,-7  ;-  ,*,(  ^ c.:.’  X'rV.'  •;  .^a:s?'j„Xa5  ‘ x.-^Lfis  r," 

’.  . .j.J.;  ^ [.sa:;  \i<f  ^rjirili  t:'  .7i  K rr(X‘  V'J  ’^Xno\*iaoo  9l 

0.^  -ir'^  fjS.r  ^-'-  --  X,.  :ri  x«rXiir« 

Tr  - ;=Xavr  tJai.  Ir*  j.-.oo  Qi  £ jac/l'i 


Xii  Il  o'j  . "lo  a^ 


& t 


22 


EFFECT  OF  HIGH  ASH  CONTEIIT^ON  THERiilAL  EFFICIENCY 

As  already  pointed  out  the  B.  t.  u,  content  of  a fuel 
decreases  a.bout  li2  per  cent  for  each  per  cent  of  increase  in  ash 
content,  hut  the  decrease  in  effective  heat  units  actually  liberat- 
ed when  the  coal  is  burned  on  the  grates  is  much  greater  than  this. 
The  percentage  of  ash  has  a distinct  influence  on  the  thermal  effi- 
ciency of  the  furnace.  As  the  percentage  of  refuse  in  the  fuel  in- 
creases, it  becomes  more  difficult  to  secure  complete  combustion  of 
the  good  coal.  With  a reasonably  clean  coal  and  good  firing,  we  ex- 
pect the  ash  as  removed  from,  the  grate  to  contain  approximately  25 
per  cent  of  its  weight  of  unconsianed  combustible.  As  the  ash  con- 
tent of  the  coal  fired  increases,  the  percentage  of  combustible 
lost  in  the  ash  also  increases  very  rapidly. 

This  reduction  in  effective  heating  value  for  increasing 
percentages  of  ash  is  shown  graphically  in  Fig.  1 reproduced  from 
a publication  of  the  J.  G.  White  Engineering  Corporation. ^ The 
first  column  at  the  left  represents  the  heating  value  of  ash  free 
coal  of  15,000  B.  t.  u.  content,  the  other  columns  represent  the 
relative  values  of  coals  containing  varying  percentages  of  ash. 

The  upper  section  of  each  column  represents  the  loss  due  to  the 
fact  that  the  ash  replaces  its  weij^ts  of  combustible,  the  second 
section  represents  the  loss  due  to  unburned  combustible  matter  lost 
in  the  boiler  ash,  the  third  section  represents  the  normal  loss  due 
to  the  fact  that  steam  boilers  cannot  be  operated  at  100  per  cent 
efficiency.  The  lowest,  black  section,  therefore,  shows  the  rela- 
tive commercial  values  of  coal  containing  these  varying  percentages 

^Clean  Coal,  The  Effect  of  High  Ash  Upon  the  Thermal  Effi- 
ciency, Amount  of  Boiler  Plant,  Amount  of  Transportation  Equipment. 


‘ 'JxldiJCI  ' , 

. . .*  fii  j 

•! 


k 


Sr/t/'sA  Iherma/  Unites 


23 


15000 


12000 


9000 


6000 


3000 


0 


4 6 8 10  12 


Cent  Ash 


Loss  CfUG  to 
^incombustible  Ash 


I Loss  due  to  Carbon 
/ corned  off  m Ash . 

Loss  in  Softer 
^ eperation 


Heat  available 
> for  useful  work. 


16  18  2! 


f^eductfon  in  deaf  values  due  to 
presence  of  Ash  in  coat. 


{j\  -sigto  zV^\  f ^ 

V^  Vfiorvtv'^l^ 

' 1 

i 

W\  zZi^l 


Awid  i 
[.  \u*t^2u  'vi^  V 


^*5ir  ■ 


* V-'^ 


(c: 

: J>_.  ■'“i'*«^ 


H’^'7 


ft 


’'  ' Z*av)\<ciy  rs\ 


24 


of  ash# 

This  reduction  in  toiler  efficiency  greatly  increases  the 
amount  of  coal  that  must  he  purchased  to  produce  a given  amount  of 
power.  Using  the  best  coal  containing  4.0  per  cent  ash,  approxi- 

I 

mately  3 pounds  is  required  to  produce  one  boiler  horsepower  hour, 
and  with  coal  of  10  per  cent  ash,  less  than  Si-  pounds  is  required, 
^en  the  ash  content  goes  above  10.0  per  cent  the  increase  in  con- 
sumption is  very  rapid  until  at  21  per  cent  ash  the  coal  used  per 
boiler  horsepower  hour  is  5.45  pounds,  80  per  cent  more  than  with 
4.0  per  cent  ash  coal  ejid  60  per  cent  more  than  with  10  per  cent 
ash  coal. 

DECREASE  IN  CAPACITY  OP  EQ,lJIP:vISNT 

The  greatly  increased  amount  of  hi^  ash  coal  which  must 
be  burned  to  produce  a given  power  output,  when  using  inferior 
coal,  leads  inevitably  to  a further  loss  by  cutting  down  the  capa- 
city of  boiler  plant.  It  is  impossible  to  bum  a sufficient  a- 
mount  of  hig^  ash  coal  on  the  grate  to  produce  ths  same  power  out- 
put as  is  secured  in  operating  ?/ith  clean  coal.  This  is  possibly 
the  effect  which  is  felt  most  keenly  by  the  plant  operator,  because 
in  order  to  produce  a given  power  output  with  dirty  coal  he  requires 
a larger  capital  outlay  for  boiler  plant  than  v/ith  clean  coal. 

The  publication  of  the  J.  G.  V/hite  Engineering  Corporation 
referred  to  above  gives  the  following  data  on  this  phase  of  the 
subject;-  V/ith  coal  containing  6 per  cent  ash  eight  500  h.p.  boil- 
ers can  be  made  to  generate  300,000  pounds  of  steam,  equivalent  to 
a peak  load  of  15,000  to  20,000  k.w.  If  the  ash  runs  hi^er  than 
6 per  cent  nine  boilers  must  be  operated,  above  10  per  cent  eleven 
boilers  are  required  and  with  coal  of  above  18  per  cent  ash,  nine- 


I 


► 

I 


i'j  f ::i 


■ : n -v,- 


C." 


% 


' W 


, ..J  j-no  2-j»q  OX 

‘ I.  .n  iqc'i  Vil-  . ^ ^i.;  . 

t irr-TG  • /:  io  , 

' - - ■(  ^ j,  , . . 


25 


teen  or  twenty  boilers  are  required. 

The  extent  to  which  these  various  items  of  waste  enter 
into  power  plant  operation  may  be  summarized  as  follows;-  In  order 
to  maintain  a given  output  of  power  and  take  care  of  a given  peak 
load  requirement,  the  use  of  coal  conta.ining  20  per  cent  ash  re- 
quires twice  as  many  boilers  as  will  coal  of  8 per  cent  ash,  70 
per  cent  more  coal  has  to  be  purchased,  70  per  cent  larger  frei^t 
bills  have  to  be  paid,  70  per  cent  more  coal  has  to  be  handled  and 
fired,  and  three  times  as  much  boiler  ash  has  to  be  disposed  of. 

These  two  specific  cases,  the  one  of  a use  of  bituminous 
coal  for  fuel,  and  the  other  the  use  of  a coal  for  metallurgical 
coke  will  serve  to  show  the  great  losses  incurred  througih  the  use 
of  coal  containing  an  excessive  proportion  of  dirt. 

In  any  case  the  ash  constitutes  an  extra  bulk  and  wei^t 
of  worthless  material  which  makes  extra  expense  every  time  the 
coal  is  moved,  stored,  or  handled  in  any  way.  Generally  speaking, 
the  loss  due  to  this  cause  alone  is  sufficient  to  pay  the  cost  of 
washing.  The  saving  of  this  waste  and  the  increased  fuel  value  of 
the  washed  coal  is  enougjh  to  justify  a sufficiently  hi^er  price 
above  that  of  the  raw  coal  from  which  it  is  produced  to  compensate 
the  mine  operator  for  the  expense  of  operating  a washery  and  for 
the  loss  of  tonnage  in  the  refuse,  providing  reasonably  clean  ref- 
use is  made. 


^ %»r  m'  ' 


. • ~ j. . rft;  •<  iin'.'  :* 

1>  r>n!:,-ifl  0j0*'ts9  >.  . r''^;:r7  uJ  J 7 '* 

r-ii:;!  , ’'V.;.  I . :•>  oj  :.»L‘  -iaqo . jrjuTf  .-. 

• ,,  XT  .-Cl  ‘W  C.  *5:“  w-b-.i^‘JO  A i'.i  i r\lAiZ  o: 

; f'>  i :ti  . : :; i gCo  to  i s , w 

■ o G .C/roo  Lli*  92  C'l’txiorf  XOW  ? • BOIa  ^ 


■*,  ■-.  > 


T /;i 


r V 


-v;!/  *' 


n-r 


0 ocJ  .’>.,  ,-f  Xboo  e:-i  wner 


/iliO  t.-'..':  »'»  ' (:«  ;';u  i.3r.'  V'X  rc 


-■-a 


ft'i  '-j 


'"^“:;:*!i"  •-!  ■ 0^  2,33  /is  i . 't .-  ',  1 a Cf  rfr>U.'5  G£  .'.•xlJ-  »3ir  ‘ b-  tr.«lX  : 


r.' 

li- 

. j 'V:  1 j 'L,  u'! 

J *'  i 

, — <0-33  oitXx-«q3 

OV*  SO  Off? 

■ ’ '-  ■ 

ft 

!>: 

J.  f'  ■ .-■  ‘‘'J.Ci  w j 

-C-’Q*'  0 

lo  ^azj  i>ni  -x.^  Jc  nr^J 

Isco 

’t 

b "•Gt'i.'-'joi 

•:.  3 'jT  •/  ^ oi..*  •;?.  . . 

^ • *i  • 

•■'J'  :.'',--I.'*iO 

Xliv  oiloo 

fi 

<1 

h 

A 

to  3 ■ 

' J'£,.:(TO-l  , c3TX  ;..  .30  3ii  .Ori 

; - . i i'-'  i ti«r '.  c. 

C ; 00  't  0 

II 

' ; hIl' ’ 

'I-V'lJ  . ^ 

‘3C  '"f^S  £?'l'.  'V'i 

.'  3 V.';  : .rl 

1 

li 

;! 

*1  Xa 


M 


'C-X 


•..n;i  -.1  0Q,'.'i3  .;t_ 


-.1  liiQO 


.'to  J-  %yq  c-  * : 1 ‘JiVliHi  'Vi  -...ul-v  -jiyJ  oJ  «»<flb:  v.,.  m o-'i: 

'to  Cvli- 7 .1  ■^■*r  b!  to  y\:iXY>:‘.i  . i;t3G.:^T 

• - - ■ 

o jJr.  ‘i.:niul.d  x^.^  ■5X07t‘‘‘ua  *j  v;'i  ^ J""; w c-v  ti  ,o.tt 

■■  1 *• 

if‘n*)r'7^oo  Ov  iii  *i  .'‘k  ii-.w  r:  o'tl  X^ioo  wjri  ©'■  ] 'lo  yro^f^-, 

'Tot  ;■>  .'>4  3 r,:!iJ  S^otjo  to  -I'.-GOiTXO  'j.’JT  -ret  '£CJ3'£OCJO  a.u 

- ^ Vx  rTo3i3  Yl-X'.rtC'.  ...‘tivo'r;]  ,«-)■;  {/!«»'?  o:ij-  l.l  ')^..>a;.OJ  io-^bOj£  orir 

' • > , /.  ‘ . GX  99SJ 


i‘ 


26 


CHAPTER  II 

THE  COMPOSITION  OP  COAL  AS  IT  EPFECTS  WASHING 

4.  Structure  of  the  Coal  Bed*  Generally  epealcing  a bed 
of  coal  is  laid  domi  in  more  or  less  distinct  and  separate  horizon- 
tal layers  or  benches,  adjacent  benches  being  separated  by  the  nat- 
ural bedding  planes,  which  probably  represent  a temporary  interrup- 
tion in  the  deposition  of  the  vegetable  matter  which  formed  the 
coal.  Sometimes  a layer  of  mineral  matter  is  deposited  between 
benches  of  coal  in  the  bed*  Such  a sheet  of  foreign  matter  may  be 
only  a thin  coating  of  clay  which  was  deposited  on  top  of  the  lower 
bench  before  the  layer  of  coal  above  was  laid  down  or  it  may  be  of 
sufficient  thickness  to  separate  the  coal  deposit  into  two  beds 
which  must  be  mined  separately* 

Between  the  well  defined  bedding  planes  which  separate 
the  deposit  into  benches  the  coal  appears  to  be  made  up  of  hori- 
zontal layers  of  material  of  somewhat  different  structures  appear- 
ing on  a vertical  section  as  alternating  bands  of  bright  shiny  jet 
black  coal  and  dull  coal.  These  layers  vary  in  thickness  from  a 
small  fraction  of  an  inch  up  to  several  inches*  This  banded  struc- 
ture is  shown  in  Pig.  2,  a photograph  of  a lump  of  coal  from  the 
No.  6 bed  near  Benton,  Illinois* 

These  alternating  layers  of  bright  coal  and  dull  coal  are 
designated  respectively  as  anthraxylon  and  debris  by  Thiessen^,  who 
has  shown  by  microscopic  examination  that  they  are  entirely  differ- 
ent in  structure. 


^Structure  in  Paleozoic  Bitimiinous  Coals; Bureau  of  Mines 
Bulletin  117. 


. > ...  . - 


iriincAW  \ ’,  ,;•  ::C't;  l«f;iT 

. - ’ • - J V ■ 


f 


• \;il:Ls^  . Tor^O 


A’l  »‘ 


oId  ca  S I u..- Ou  i>f’  • 

0.  3l*  v: 

0 *5D0 

ti  ''  e -X  ■ Di 

j.'X  V‘X  ^'.r  ’'z.\‘i^H. 

" .•i  ,> ..'  ■’o ''o,...  j' ,X 

( 0 •''.  0 • . 3 ^ X V - ^ .L  "5 

- ; ,. 'X‘J  ■'X  Til  ■'"S,:*>'o-  ' r'"*  3 

J-r 5 '■•  .'Dr;.- f*i  " Z 

r:o  ;pj- 

4,  . , .--tv.. 

■J.  X '£  r .';>  i,  ' 

roJ  -'  ■'  ' i ''■' 

n l.‘  ‘lo 

.tox.U  iOqob  D 'i 

'"— -i 

;;fC 


¥’ 


no--  i 

t 


• ^.' 
? . 


fi 


1^ 


J ^ :.'  : h ,3  ^ :.'  t ' 


ax  r.ioo  'ro  '3  or(a r:"-j  ■" 


or  O-i*  *> 


0 -.;c  X 

iTO  :; 

Ji  -f 

.T  b 

* 1,  • %(*>•  -J  w 

- ' ■“  -' 


io  ■uviid’.i'oy  (ti 


tj  yJ[i-o?  I 


t, 

» 

i* 

dJ  •' 


'.aw  v'ucTn'X' 


a&oi  jvr.r  cj  -.i 


'id  'X;;  <.  U ‘ DC'*  0'S  O'!  erf  rfoi:i>M  |j  ■ 


Off*  orfai  iqoj  .cj  jI  ilirr 


-\*, -Ji/’ 5CJ_X  fj  ''.:ai?rf  J r;,''.*  f 


'•:  :i  -05  rf*  03 ..  .1 -r  i^ov  ' aoc  .t 


\*  .. 


Oi<  'i  : 


.f.  X'^Uv*  'Jn’v  o^ai  j/fe  .' 


o 


X »»X  .K  y w ;oJ  I iO  & 'C 


DC: 


.[7  : J J'X;.'J  Oa-'TJU  ;; 

X 'I;  •i.rfJ  1v.  r:>  .iX  j\;:  r .^J‘•l';D7  C *i  ..poia  o .---  T oiX'tr)'/  .-j '^Dx  »■ 


xi  ;iOx  l/'!io;-;.f^,.l;  Ir  dx  \'£  v 3X';.'c  X onoff,  . co  j.:,;:,)  ^;:v:  S.^00  | 


-Q 


■)c  5 J.  "r 


ZOiJl 


0*  3,!x  :.-  iu  .ioxjd  ’i‘X  Il.'iJ::?;  r 


'<  j 


IV':.-  /-c:^  X.^oo  Xu,  <^'L  ^4  *>  j rfcjjr  o oriu  ■ , . .oJt'i- /;?  a-=,:;;.o  oi  , r I,- 


' . , ■-OX-^o  j.  T..  jj: 


‘i  ' I.  ior»  livh  ,jbn‘:  Ij  .0  Xil^xT'f  to  *nxax'’X  .•  ./i : .S'.  7 0*7 o fir 


c. 


'.VJ  ';a‘£  S:  .:■  f;Xj.'*X4‘trrX ;:  5 . •.:  J 'K  j v"A  J .v30  S/.  j-iir- j rf 


1: 


-D;-'l’.:  :•  ■'  oxj  ^»nj  X.  aX  .ao j e „aiir'..r^&  oxcoo?.: o'y-jira  ^ 

”•  -,V  ■•  ■*-  .,T,^  • ••  . . ' 

‘ ■■  S . ■■„.?■■»■  D;/'iXn  .. i Xns 


«<  I 


c«':x’'  'lo  t/ssx  . e • ;Ix*or>  c;.;oai-3ff.;ri  . -oOfiX  t.’:  3X.  / n<' -rX®  X [ 

f ■ .S  ' -.r  <'S-r 


26 


"The  bright  coal  bands  represent  parts  of  definite  compo- 
nents of  the  woody  parts  of  plants;  that  is,  parts  once  logs  ofy' 
stems,  branches,  twigs,  and  roots,  but  now  much  compressed."  The 
dull  coal  layers  are  composed  of  very  thin  discontinuous  strips  of 
bright  coal  imbedded  in  a ground  mass  of  finely  divided  material, 
the  atritus  resulting  from  the  disintegration  of  vegetable  matter 
in  tlie  formation  of  the  coal  deposit.  This  banded  structure  has 
been  recorded  and  discussed  by  various  investigators  since  the  time 
of  Witham^  who  was  the  first  to  study  coal  in  thin  sections. 

Very  thin  layers  of  charcoal,  highly  carbonized  woody 
matter,  are  found  on  the  cleavage  surfaces  parallel  to  the  bedding 
planes  of  the  coal.  Ordinarily  these  are  so  thin  as  to  be  hardly 
discernible  in  the  vertical  section,  but  occasionally  charcoal  lay- 
ers of  appreciable  thickness  up  to  several  inches,  are  found. 

These  appear  on  the  vertical  face  of  the  coal  as,  charcoal  or  moth- 
er of  coal  bands. 

In  addition  to  the  division  of  the  coal  beds  into  hori- 
zontal layers  most  beds  show  one  or  more  series  of  parallel  verti- 
cal planes  of  cleavage  which  determine  in  a general  way  the  direc- 
tion in  which  the  coal  face  breaks  in  mining.  Subsidiary  to  this 
major  system  of  vertical  cleavage  planes  or  fissures  in  the  coal, 
which  is  often  characteristic  and  continuous  throughout  a given 
seam,  the  coal  in  place  is  traversed  locally  by  a more  or  less  uni- 
form network  of  planes  of  weakness  generally  referred  to  as  joint 
cracks  or  joint  planes,  ^«hich  determine  to  a certain  extent  the 
size  and  shape  of  the  particles  which  the  coal  naturally  breaks 

^Report  of  First  and  Second  Meetings  British  Assoc,  for 
Advancement  of  Science  1831  and  1832. 


* • ■ s:c  -.'..‘i  . ntrr«!r; 

to  a."  CX  »?J'r  , i>  1 \,  •*  I y’^ocir  v..:  t . < 

'•  - '•  -r  ; no  r^Utrr^*  -rci:  ^ ; . ' . O'X  v , i':-  , , ,.:ol  i 

•' •i*r;5  : .•-‘"’f'"  .*t;^  vii''  ,;rv/  ’to  ->3 '^.o  rnioo  oi : r : -,  v',r*i  Xj  c?  IX. 

• * ' 

. . 0;b:-.  ,1:;  Xl'lo  ’>.1-  : '>rtUOnr^  ' : ’ nl^/iObOo-igiu.^  X,-- 00 

• • ''V/  1 ,:t  ::oi j -X  J ..  -x.*  '-.t  .*  ’^■-  - 

m 

' * 'rr  ...  . . i;:T  « .•  Uocr>.o  £>ioo  1c  r>ot.  * •.  ru 

-I-:*  * .i  ' • . b>  bri  j /.  ..oei  no  ■ ■ 

, . t .Ut  *X  I/OO  X'»X'.’S  oi  J.ItI  : r.'-  .;  ,.r  I 

' ■-•  ^'‘7-  ■-  ' , . v"?'i  .Jo.  1 V vi-r::,..-.:  aiJx-  'c-reV 

' ■ ' '^'*1  ' ■'  ' -r;.  ‘.V  ;ji2  .i>xU  ,.o  b aot  ot  ■ ,^o*.r  ■•• 


'.'■'  - Vi'-  V 


ViO--;? 

/ 

I.-.4C01  *' 


‘ >'r  •'i**--  •'  .6;-.  ...J  -K  ^3;LsXq 

f: 


! • . r « 


O'.'i  ';, 


: ■ icno  JJ  , iciJ;v;  >i  X*-  o t^ToV  o.  * ' .-.i’  •. : Jx/tiojni  b 

, r‘^0i3.L  I .'t’r*:*v3  ->.•  oi/  t»X  i. -r  nd^tijiqfe  ic  a x3 

< *•  ^ i •'  ■•''  1 Xi*oi^‘ir>r  r*'.-*  na  i > ua-jn'r 


r* 


I 1’o 


-■'">•■:  r r,30,/  I^co  10  ..'Oftfivtfc  '..  .:  hi  tt,t  ,a 

-i-J-:  - 1‘^rx  .^oriu'  evr.:.  - o -r,-:-  3 ; . ; xi  Uincs 

•,;  .tr  I J-T  • ir^3  lU  ” J v;»  lo  I.r-o 

i 

n,.Xr  c*  y*i  Xb. «<:-■.  nl  ';.,.:e7;  •':  I - oo  oH3  i.oi  > r:I  noi^ 

' ' * '■  ■'*‘•'23-1  ‘ raotj  1o  ■:^:f!3\;a 

’-''''■.  '■  U.jC'%;.f  XiV.'j  or.ix  OiJ«i*r3**Oo'l.w':o  »;?'  tioltih 

,f  . xo  ' 

, ^TT  j ' • X 

^ ~ ''W»>  » A '-/  ' i ..  M ^ 

ki/ 

' ■ X>->-'  iO'J  ~ oj  90i  iT’ -'ll  <>r>  .*:'  j «3.',  -.  j. 

J.  Vi  r./.-c-.v?/.*!  .f  -^3  «'olrtw-oo.:i>J:iio<;*  =»*-.  to  ©.;•  .n  ti.;«  oxifl 


-.f  yXI-.iObX  btven9V;rt«  ..  ••  f-o.::!-  ri-X-..o 
OsL  -HI  ■ ;^i.©;.,  I O ar,/;  i q 1o  -Jt  UTOl 


. ' I i 1 ^ ttT:, i ■*> *' . b . 

c».rr:  « 


oi'u.  r.i 


':I'I  ,1c  ♦in-^  ,.  - ..! 

X ^ w*  X ^ ->  ■ ^ V ^ d 


29 


into  ^en  crushed.  This  sometimes  has  considerable  significance 
in  the  washing  of  the  coal,  particularly  if  the  impurities  consist 
chiefly  of  mineral  deposits  in  the  various  types  of  fissures  de- 
scribed, of  if  the  cleat  is  such  that  the  coal  and  the  interbedded 
impurities  break  into  particles  of  different  sizes  and  different 
shapes.  In  some  coals  this  tendency  is  sufficiently  developed  to 
make  possible  a measure  of  separation  between  clea.n  coal  and  dirt- 
ier coal  by  screening  out  certain  sizes.  An  example  of  this  is 
shov/n  in  the  following  table  giving  the  percentages  of  ash  in  vari- 
ous sizes  of  coal  screened  out  of  a sample  of  raw  coal  at  an  Eng- 
lish washery. 1 

TABLE  2 

Raw  Coal  Screen  Analysis 

Size  inches  Per  cent  ash  Size  inches  Per  cent  ash 

- 2i  16.01  1 “ i 10.03 

2i  - 2 16.42  i - T 15.41 

2 - 1|-  11.97  t “ i 16.89 

If  - It  15.83  * i - 1/10  16.67 

It  - It  13.16  1/10  - 0 20.85 

It  1 1 8.75 


The  structure  of  the  coal  bed  and  particularly  the  way  in 
which  the  impurities  are  incorporated  into  the  coal  deposit  has  an 
important  bearing  on  the  washability  of  the  coal.  Most  of  the 
coarse,  removable  p#irticles  of  refuse  in  a raw  coal,  as  crushed  and 
prepared  for  washing,  are  the  broken  fragnents  of  interbedded  or 
subsequently  deposited  sheets  or  veins  of  mineral  matter,  shale, 

limpurities  in  raw  coal  and  their  removal,  - Drakeley, 
Coal  Age,  July  24,  1919. 


•a 


I It- • o.e... 


:l  -ell 


:o/t«r  o:fr? 

i'’82  ’ j iJ  at 


p ij  ' * * : . ’ . 


’ • -J.t  •?.  JO  Pin"' 

■*■  'oiJ':  5 -‘oo  or  ' 

‘ -..  oi"r.:v  ?rf.*  •.  i c)^iso<j»b’ vX’ldirfc 
,u  ;)  r .V'  iVjxir  M‘  c?rDln  6rfv?  ':i  1 
v?.- . i:»i  •.  .■  W_iii  3C»8<»^^r  I'th''^:: : 

'-  ' •'  X t liJD  iiS.i'0'j  Cfi-lOW  ^. 


~.  I 


•''  ..'  .A 


V 


b - ». 


1 


-10  r;  /-£c  ixa  .'  ."o,  r :c  ;i'rr ’5>'.a*r,  oXJiaaoi 


y L.  r:i  ;i.t  1 -i’  t'ti^.|:  -> 


V .X  -A  -i  ic 


' n 1 '.i  ;=.  '.t*!'  > _•  t 


't . L'  x<^’*  ■•  '*00  'i  -» . 


:’:otoq  :}  -li' •.  -. iol  *rl' 


.i--  J,:  I.’i-o  "'  •:  10  nf 'T^i; 


' X.,‘.i'"'0  ’to  ' ':;/c 


o t 


nlf!  X.-f-A  .‘-''■'rnH 


. -1 


Td.iiJC 

ric* 


C-C'. 


^ r 

~ xV 


r 


_ J.o 

r* 

_ j 


I - 

X l-il 


' ^ ’1-^'^  " . ’ C .t  ;r;;i  X.i'Ov  v '■',  * 'Tc  1117 Oiil*  ,-^u  ' ' ' 

'*  ‘ - *-rr  ‘ 4|  • 

h.“.  ' X i . X-100  90J  “'J’rii  i>(>  j i-n  j:  '-yi-.  r* ■?  1 ♦ .'loiiiv 

:i'-j  .cuiJ  ;o  J.i.fa 'Ttv  :iu  ■ 7 iUttotrrf^ 


o .If  . 


. 'j  r.  V 


a/uTC  ■!  . 


Xc  aelot^i:^  yrlMTa^  . .oirxr  .'o 


I).*':;  •-'.X  ,' ;v  ; r.OiiO'Sd  e . , iXtIli.v  io*! 


. Uy. 


■:x'-  ..i  I.  i/fliov  ;ro  fto.;  >tiO(js6  ^ | 


30 


1 


slate  or  py]^te^^^ccurring  in  some  of  the  above  described  crack's 
or  fissures  of  the  coal  bed. 

general  the  impurities  break  irregularly  into  pieces 
of  variouls  sizes  and  shapes.  The  coal, while  forming  also  many  ir- 
regular particles  of- all  sizes  down  to  the  finest  dust, has  more  of 
a tendency  ^to  separate  along^ [^finite  cleavage  planes  forming  a 
larger  proportion  of  cubes  and  prisms  than  the  shale  and  slate 
with,  as  a rule,  fewer  flat  pieces.  ^ 

The  first  breaking  up  of  the  coal  bed  occurs  during  min- 
ing,  primarily  by  separation  along  the  principal  bedding  planes  in- 
to horizontal  benches'^  which  at  the  same  time  break  up  into  blocks 
or  lumps  by  parting  at  the  well  defined  vertical  cleavage  faces. 
This  is',  of  course,  accompanied  by  the  formation  of  more  or  less 
dust  and  irregular  broken  sizes  of  coal. 

Then,  in  ©rushing  preparatory  to  washing  there  is  a cer- 
tain tendency , more  pronounced  in  some  coals  than  others, to  separate 
along  the  minor  bedding  planes,  the  boundaries  between  the  dull 
coal  and  the  bri^t  coal  layers,  and  at  the  joint  cracks  perpendic- 
ular to  the  bedding.  This  Is  not  intended  to  advance  the  idea  that 
coal  breaks  only  along  these  definite  lines,  but  there  is  a decided 
tendency,  as  described,  and  consequently  the  detail  structure  of 
the  coal  determines,  in  a measure,  how  the  coal  breaks  and  what  is 
more  important,  whether  the  coal  and  the  dirt  break  free  from  each 
0 ther. 

If  the  impurities  in  the  coal  consist  mainly  of  mineral 
deposits  in  these  various  cracks  or  fissures  along  vdiich  the  coal 
tends  to  separate,  they  will  generally  be  exposed  when  .the  coal  is 
crushed,  and  the  chances  of  a large  proportion  of  the  dirt  parti- 


• i a 


• ■ ^ fi'iU'-M;-  "iQ  eaio«  a. 

« &'  --  ■TL'31  f . 10 

Jn:  XlT 'A  -j-kJ  2 iJ  1*1  tfr j £a^p.T>:^-  fll-  . .:  *^V 

05<  4;  fiiir'",  . . 0 . .^rfiL^/x;Q  ^dsjcb  *lo 

.*  '1*  w ..<*»  i Ip-  iiipl  y 1 J ' 1 ~ "7  't^Iu"3*.  *, 

-i  :' > r:  M.2l  ^ 0 j 

.^i*  -)  '/A  .ir.  I i'..;  2et  :■  _>  lo.-f'j:'  :.  tioi^ioijol .r  is^'! 


•> 


■- 

‘ *•  - » 

' - .:  J .a*>  -xc-r  k 

. -n  4 : 

" 30  D ‘ : 

i ICO  • . v' 

• r< ^ •'-'•»/  - ■*• 

3ii: 

* * 4 

Ox  »> 0 ^ G 

•■  .Icj'  0:,: 

, ; 

C'l) 

{ :.  tt 

z*  r:e^  ak.j 

,i-'  t Xnonilo-  cf 

» .'■ 

■*.'  - ^ 
f 

> :?  .■'!.:o j 

'lOY  i C.M 

/fn  - * 

Z>'.' 

•1„  :’0;j 

v:.?  v/i 

: 5i  ri.»;i;.3o:.  o x^'  , 

■iuc/'o  'io  , t ,•'.  .*JT 

• 

.f  ^00  -'aO 

nc*“"oi 

. x-.v'.-iniii  t.L-w  Xuj'vM. 

-*• ' • 'i  ,1  n t 

A^’ 

- A 

^ . 

^ 4 . *» 

.’J 

, .tj.ii  ....  -.^  , 

i:  -’o  '.’••'i'  ro.'>'”:o>  ■•.  • j •;  cb.'iiyc-J  a.\  , • • iCiiiifS  e.w  ;gnoI:?. 

3--^o  i-'  :-.5ioi,  .^rii  Ja  a J)iu.  Isou 

■ •■•;-.>-■  i :i.‘J  Vi'.  P.T  -i  So;  kI  a;.ui'  * .i.>i>wS  oS  z Uu 

, 'T  . ■ 

r;i  ‘rxD;'j  :'  , ' 5.5 1 £; ileij  shsJ^  \;I;ro  S3t«=^sii  iv-oo 

!'.5  t*i  , b e-i  JK?  ,:  :»t> -Jigir' 

':*.v  b.i9  ai.’.^zd  ..u'O?  'mow  , ■'ziia^z'ir  li  «i  , Xapo 

\5.  --  r.;e'xl  ar-i‘i  ?L:0-:  ^ r'i  - -b  t-  cj  i»ns  I/;oo  o/j  le  9t0fSi 

•»  • ...  A ' . ••■»J.p 

• ■ 'i55 

• ■'"-■•/  : ic-  vl.'iiisi? ~rL‘  :;j.  3 rJtr  iiiiqxtd  btIS  '-I  ^ 

i<»0'2  Ti?  rroir^t^  •’•..'ol  ^©‘rv'ijsi'^  'rn  Cl/oil-.v  iU  " 

i>‘n;  OfTX5  ‘of  '/.f  Xni'i.isi-i  xxi;v?  x^rif  , j -rx  • 7- -s  ds  < ^ 


31 


■becoming 

cles^detached  from  the  coal  are  favora'ble*  In  many  cases  the  natu- 
ral cleavage  is  "between  the  coal  and  the  dirt  so  that  they  break  a- 
part  easily  and  cleanly.  On  the  other  hand  the  coal  and  the  dirt 
may  stick  fast  together  so  that  it  is  easier  to  make  the  fracture 
in  the  coal  or  in  the  dirt  part  than  at  the  contact.  This  results 
in  particles  part  clean  coal  and  part  dirt.  Fortunately  the  latter 
condition  is  not  as  common  as  the  former.  A coal  in  which  the  im- 
purities generally  stick  fast  to  the  coal  in  this  manner  is  thereby 
rendered  very  difficult  to  wash.  A coal,v^ich  is  principally  debris 
or  in  which  the  laninae  are  very  thin, is  somewhat  more  difficult  to 
wash  than  one  containing  a large  proportion  of  bright  coal.  The 
dull  coal  breaks  more  irregularly  and  more  finely  than  the  bri^it 
coal,  vsihich  forms  a comparatively  large  proportion  of  approximate 
cubes.  In  general  the  higher  ash  parts  of  the  coal  break  into 
smaller  particles  than  the  cleaner  coal.  For  this  reason  and  be- 
cause of  the  large  proportion  of  slirae  formed  from  the  clayey  im- 
purities, the  hipest  percentage  of  ash  is  found  in  the  fine  coal 
or  slime  where  it  is  the  most  difficult  to  remove.  This  is  illus- 
trated in  Table  2, which  shows  that  in  the  particular  coal  examined 
the  material  which  passed  through  a l/lO  inch  screen  contained 
twice  as  much  ash  as  some  of  the  coarser  fractions, 

5*  Chemical  Forms  of  Impurities  in  Coal.  As  already 
pointed  out  in  the  introduction,  the  chief  concern  in  washing  a 
coal  is  in  the  removal  of  the  sulfur  and  the  ash  forming  minerals. 

The  sulfur  in  coal  occurs  in  three  chemical  forms,  namely, 
in  chemical  combination  with  iron  as  the  bisulfide,  marcasite  or 
pyrite  (FeS2);  as  a calcium  and  sulfur  compound  gypsum  ( caS04. 2H2Q) ; 
and  as  an  organic  compound  in  combination  with  the  carbon  of  the 


-11? 


, ' B jr.r  'I 


'C*Uvn  . Ja'xov.  \ n*is  £Bt  • zLli  jl<;;'i*  l>' 

...^.ixi  \;onr  ijAt  !,...•  X.i;oo  q4^‘  .'tiSKwO^  a* : /■ 

- *>*■!••  • ■■■■;'-  ^ r ',' 

*I 

^ »■■'•.•  li’  ?'  ni  *l  ,-  , J C-?  ‘t‘:'u*C~OJ  ii."'!  HDi^a  \*ff  || 

w ■ " i' 

V-J.t/IOT  ...  . . > ,:^-w'J  n-'r  +..  r>^,  .r  .^o  341  ’,u^'  ./ 


t£>."  .*-  .L 
1 ^ 


r.L' 


'.Xov  .''.i;j-i c'i  ^ - J ’I -:.j ■ ;^.ipiii  tsoo  r-;iix&  *?Taq  i>i 

r 


. "XO'  af  fto  -^0  0 ;cn  ei  .;oi.?ir>“" -> 

'•  ^ ^ J - 'o*  ■?«=•:  • tain,  -ac^ruroa 

~..U  I.  .,v  ...  >^-  \x  ^rr  ^ ^ ''  ,£  '^5  3 A . "S^  it*  UOl'i.  ii.;  i>  UTC  .';Dr!l.’ '.I 

?5  .V-ifOX'*  ..iliiiJ  9.H,-a.-I  :.  ‘ :"j  /OXf^  r!  -XO 

■ *•  -.‘■‘ti*--*  ■•  - qcX^*: Tciq  •'■: '.-‘J  • a ; .irrix v!:c'.  »oo  .-uBr(*  r'r  , 

•-  * ^ ^ •■•  ; ’••  V.  ' tl  TS  ii.i.';  9101ft  fTr  ■ •;-  I.-ioo.  .C‘>-A 

* •'■  * 5 

AO  iu:::..’_r-i  ....•-  4 Bsr'Icl  . :.v?'  ,,u;oo 

Xj?cc  :j  .-i.?  iu,  _ i i/j  t:., ad^  ,.  A-r'nt;;-.  /,  ' ' ,??eo'iio 

n<-n«ei  ■ rnJ  t;  ■ ••  . *0*.  ^-:.0  iiu.’  ix  .-;  -inxi  j 


^ t,.A 


ii 


A dfit  Ji:ox^  L - - •::-ir*,  i .)  ..oi.f tr^c-v  * . a;*!::!  9r:s  to  ^ttu^ 

* :-u:  t».:i  i . nix, , j .:.  „^iri  c,;r  . 


- *;i:x  Ai  3i,:^ 


*/  3.  itXuo.i.  t . Jj  j 2 iii  9, .’  gj  olor  ?rxiX»  ‘i 


(C 


*''-^-’•.7:^  I :o:.  -i  ..  'lO.*  nt  .t ..  • * , e^-orfu  ito  r • . -9.!:X£T  ..i 

■•■  -. . .’rc'O  r.'j^'ton  ^ oi'ii  C'l\l  a ^ofieA3g  lirv^,  ' 

, ■’oi.  ' 'r  V laDiiJOy  fiii*  '*  ■ \::o€i  h^'‘' ■'  rJoi/aft.n:.  ooi^-^ 

' ^'  ''  ^ *A -’ -'A  Ix£  ' ;^x_0  £ H 

i.;-x:’-ae-  -re  'l^irto  <jz  J ..qoit-oxiiiOiJ  ,iX  pi  = / r;j  j Jov^S^ni oq 

^ i;i  -r '-  '.:  luliuji.  r ■:>  lo  ,X*T'.  ;■  " :■  • *.3 

r.  r ^ i 

■ .-■  f -L  - :'l  r-ri  vx;..  r,,(,o  •£;'XI‘./.n  />nT  . ^ *''  *•  -,J. 

5^  .».x:3-r3i:r  , *XIyfl2rf  'c-fi  «u-a.  .♦Xvt  KoijA’,.,io/i..o  X/.ol.v.^rio  ai 

t 

- * ^ iOxp.7;;c,o  •xr.xX...’A;  - : ’i.'loX^^o  . .^  i)  Zi  X-X'^fT 

» - t"’ 

o;  - tc  r'.t..i\^.’j  -z^.j  ^ x?r  noX^isi"?,  Jcco  «£  bnssciiaoo  uiu»S7v-  qb  ' 


* «« »i  i*>i  iii  XiSl 


32 

coal*  In  addition  to  these  forms  some  coals  may  contain  minute 
quantities  of  free  sulfur,  but  this  is  exceptional* 

The  pyrite  and  gypsum  also  contribute  to  the  formation  of 
the  ash  remaining  after  the  coal  is  burned*  The  greater  part  of 
the  ash,  however,  is  derived  from  the  earthy  minerals,  clay,  shale, 
or  slate,  which  were  deposited  as  mud  or  silt  in  the  swamp  with  the 
vegetable  matter  which  formed  the  coal.  These  vary  in  composition 
in  different  seams  and  different  localities  in  the  seam*  The  soft 
fire-clay  deposits  are  usually  a comparatively  pure  clay,  consist- 
ing of  Kaolin  ( AI2O3. 2Si02* 2H2O)  and  a little  fine  quartz  sand* 

The  shales  and  slates  are  similar,  but  with  varying  amounts  of 
other  substances  such  as  the  oxides  of  iron,  manganese,  calcium  and 
magnesium  intermixed.  The  layers  of  shale  or  slate  occurring  as 
partings  between  benches  of  the  coal  generally,  thou^  not  always, 
contain  some  carbon  which  gives  them  a dark  color*  The  black 
shales, which  contain  a large  proportion  of  carbon,  are  commonly 
called  carbonaceous  shales* 

The  other  ash  forming  constitutes  of  coal  are  the  resid- 
ual mineral  matter  or  ash  from  the  original  plants  which  formed  tine 
coal;  and  calcite,  the  carbonate  of  calcium  (caCOs). 

Some  other  impurities  which  are  not  of  direct  interest  in 
connection  with  coal  washing  are  moisture,  oxygen,  phosphorus,  and 
in  some  coals,  small  percentages  of  alkaline  salts.  The  moisture 
in  coal  is  of  course  increased  rather  than  decreased  by  the  washing 
process*  The  phosphorus  content  may  be  reduced  somewhat  as  it  is 
ordinarily  associated  in  some  way  with  the  mineral  matter  or  at 
least  it  remains  with  the  ash  after  burning*  The  phosphorus  con- 
tent of  a coal  is  a serious  consideration  if  it  is  to  be  used  for 


T*  1 


f ‘ 


:(• 


1 '0  ^ H 

-y.  ■ 


. «.,v. 


ih 


fioiitv' 


•2'v; 


~v.  u o . 


} - li 


■5,  X 


'f;'. 


."^wi 


.1  >'rf  i . , U . 


M ) 


■c:  - . 


C.'KIli  , O' 'i- 

•:u  nji? 

■,:;  LCT  ' ■ \ .■ 


. :)  ®aior 


..i  «1  J.  „ .,  ‘J  . f ^ 


35 


metallurgical  coke.  Where  soluble  alkaline  salts  occur  they  may  he 
removed  in  part  hy  washing.  Salty  coals  are  evidently  not  common 
in  America,  as  no  mention  of  salts  in  coal  has  been  met  with  in  the 
American  literature  on  the  subject.  This  must  be  a common  impurity 
in  English  coals,  however,  W.  A.  Bone  says  on  this  subject,  "Some 
coals,  besides  containing  insoluble  mineral  matter,  are  impregnated 
with  minute  quantities  of  soluble  salts,  principally  the  chlorides 
of  sodium  potassium  and  magnesium  and  are  thus  called  salty  coals". 

Physical  Forms  of  Impurities  in  Coal.  In  the  problem 
of  efficiently  cleaning  a coal  the  physical  form  in  which  the  im- 
purity occurs  has  a much  more  important  bearing  than  its  chemical 
composition.  As  has  already  been  pointed  out  the  extent  to  which 
a coal  can  be  improved  by  washing  depends  very  largely  upon  the 
structure  of  the  coal  .'uid  the  way  in  vdiich  the  impurities  are  incor- 
porated into  the  coal  deposit. 

For  practical  purposes  in  a study  of  coal  washing  methods, 
the  impurities  in  coal  may  be  classified  as  regards  physical  form, 
into  two  groups.  First,  finely  divided  impurities  structurally  a 
part  of  the  coal  and  inseparably  mixed  with  it;  and  second,  coarser 
segregated  impurities,  which  may  be  separated  from  the  coal  by  | 

mechanical  means. ^ 

IMPURITIES  STRUCTURALLY  A PART  OF  THE  COAL 

Impurities  of  this  type  are  not  separated  by  washing  from 
the  coal  substance  with  which  they  are  intimately  mixed.  The  ad-  “? 
vantages  of  a knowledge  of  these  constituents  of  a coal  are  all 
negative.  The  chief  value  of  their  quantitative  determination  is 
that  they  fix  a minimum  ash  and  sulfur  content  of  the  cleanest  por- 
tion of  the  raw  coal,  which  is  generally  called  the  true,  fixed, 


o'j  Jo--  \;I'v^adbrvv> 

•-  ..'  'i  1*',’  *0’.  Li-  :'.  i :.  i 

vj-i''  fv'i  i'.osrjsLvo  *#aj-**;  e:.i1 

3ii;rc'’  , '31  Tv:'  *tv  sv. 

5«J 


:s.iie  1.-V  ::ci/  m 

.■:ijp,  ■oti^  f:‘j  n-£  i/;. 

,;>.':lrTi4*4flOO  , c£i;o; 


- o:i 

.-■r/X-  j 

. • • 

-.1:1 

Inuii/p  .•'!•. vlfn.  r^v  .1 

• .'  7;  S«9i 

- 

L.:  '.rO*  X ■ J.  , 

UOl-  )r; 

• 

. ..‘1.1 1:1^ ‘/SCI*.  3j. 

1 • 0 • 

* k . 

;r\  . , 

',  ■ ■ Lai-t,  : ; ’ 

:. : •^  ...:  r.i)/oi':  :■  ^0 

^ oL#:l7.’l  •' ■ ’ 

.0.:'  *.•  ■’  . w ; . • ...  r*ivoi  4'”'  * 

vli*i,';: 

r-.i  '''^T  ' : J7 . j 

z.'*  :.  .. 

•*  *.'i  on  li_  : . V.-O  i 

'J  ' 

'll  A . c?iKOv  :■' 

"j  rc-n;  V C . 

7 . V'l :> . 

..-J-If):*  '.-*'  .'■> 

o\  V -i 

^l^J:  . (.'.o  X.Jou  ' 

i or.’. 

-«  i . emit  ■ 

./'jj.-TT  .rl  \' ,.v  5*  iv 

X ioi 

’’  ./■lb  , 

- 

v~.,  - ’ i ii 

V-  0 ^ 

j.'.;,  oltil  *:.... 

I ‘ t * 


, . : i :£fi  ▼ leOc  'so  x,'^u.' 


..  1 - . 0 i J’'  o ' r:  .’7  : o 't 


V-‘. 

io 

f: 


..  . 0.^  -u  r *!:•  ft  f 1^:42  f ir^r^  riX  ‘ T"  jn:i  . 

>r  ■x:.~»r.L"x.-^a  .tiiri-. 'i^xcii  i-- i « '£X ^ . 

t ^ : - i'-i  ' i’o-im  '-.eiU  Jbft:*  er«  'to 

V’  ^ L--:  J 3-ssriiik  og  \i'  Jb  , c \ J:j  liu^rL-z 

Jvj  i joijxo'rfooi’: 


JA.00  ai:  7 10  T^iAT  A VXiivXUT’JlJH?  : -ii!lTXH  J'C4£l 


» A , . 


: : V'  xi  br 

; • -■'  ■ -i 

XX  li  " I ,;  0 0 « 1 j fipji , . X .?  '-• 

i (1  ? ?:  ' ..«'  ctrf('?.';io:.  'ti.l.lb, 

- i 

''  j ■ .,  I '"O  V 1 ...  -j X ? r;,  •; 


uiiO?  '0 

ajl'; 

*■’•'  r •' 

r'-  j Aiiluv  .1X7 

OOf?. 

oasrfl;  '!<'  9r--  -. 

•**OilK 

*;V-lT  ?;rr--v  'l:>l-.'^'o 


♦ ' M 


♦ 


,i,KA  TTf-r-^t  ■ .r  :-ri'i: 

!i  ri'j.’  . , v.'-*.c  ftjfi.  to  r 


- i 


Vi 


34 


normal  or  inherent  ash  and  sulfur  of  the  coal.  In  the  washing  pro- 
cess for  reducing  the  percentage  of  impurity  these  values  for  in- 
herent ash  and  sulfur  may  he  approached  as  a limiting  minimum. 


fine  disseminated  grains  of  pyrite,  finely  divided  clay,  and  the 
mineral  matter  of  the  original  plants.  An  approxiroate  determina- 
tion of  the  inherent  impurities  is  often  made  hy  crushing  the  coal 
to  one-half  inch  or  one  quarter  inch  size  and  immersing  it  in  a 
heavy  solution  which  will  float  the  coal  hut  allow  the  heavier  min- 
erals to  sink.  Analysis  of  the  fLcat  product  then  give  an  indica- 
tion of  the  percentages  of  inseparable  ash  and  sulfur  in  the  coal. 
Some  writers  have  erroneously  designated  the  sulfur  determined  in 
this  way  as  the  organic  sulfur  content.  Powell  and  Parrl  have  de- 
veloped accurate  methods  for  determining  quantitatively  the  differ- 
ent forms  of  sulfur  in  coal  and  their  work  has  made  it  possible  to 
determine  the  percentage  of  organic  sulfur.  This  is  of  great  value 
in  examining  a coal  to  determine  its  washahility  as  a careful  sam- 
pling and  analysis  suffices  to  determine  the  natural  limit  of  sul- 
fur reduction  which  cannot  possibly  be  exceeded  by  a practicable 
method  of  mechanical  separation.  It  is  conceivable  that  this  mi^t 
save  costly  mistakes  in  the  design  and  erection  of  plants  for  wash- 
ing non-washable  coal# 

It  appears  that  the  organic  sulfur  is  united  with  two 

different  types  of  coal  constituent,  and  is  classified  as  humus  or- 

‘ r ■ 

ganic  sulfur  perhaps  more  properly  merely  asf  Phenol 


The  common  impurities  of  this  group  are  organic  sulfur 


soluble  sulfur. 


^University  of  Illinois  Eng.  Exp.  Sta.  Bull.  Ill 


. . A ■ 


^ *'■'  * --  hr  . , ^ r I I.i  ^•..  X»wat#a 

■*.  t ‘ioj.  xS  L’’i.iq:'\^.  ’Iv  {^,*j  .i'.."^o':v  ? !il^  NiTiy. %ii»o 

, c.  ..  lar..-;  ^'’Tcfq  o-  *•  > • 

V , 

, ,..  .M  o.‘ y.  7 ; £in>;  t ’.■  o ’.  ,1  6ft^  ' ; , 


Sk 


yii"?  > 


y,.i  > • ^ ^ ^ 3-iv  '!•  *:  - i 'rr.t;:!  .Xir 


J -■  Cf^  : ; • fji  , -.71  Oii^'  ..  Ic'  ;7 

le.ro  v:'X  • -i.'-i  'C  ' ■ •..  .;oJ‘io  Hi  o I'z.  l Xr:j  S'i  'fo  nox.t 

.:/.  J.  7)£ti •'>,,1..': : I,  . ;;  • '(--x  *i‘J  .,  ;;,  •>;.'>  ',7.,  .no.'ti  ‘Hxia-.>Ai'7  . 

i.  • .1  jc  .r  c'o  -V  .iT^XCi-  ' .’iuiilv  ^irjsy- 

•*y  .-' 

:■  .i'  X v.*  '.  •..  , £#i:r\  ■>  .♦..'xo  R^rYr^*V  , oj.  ."5T.:r,' 

. i.  J-  rl  T.ull''  hi.'  tc-k-  ; I;  ir  yo-’^i-TJ-noc'T'j ..  j.;?  *>0  ltd.? 

% * 

>iZ  • j t ri  ■ ' V ,.  :3’-J  .'".1  ,j  . .'o^  •yj-x  •'’  t,  \zt.:  i'V^  nmoS 

• •.'  'f  -*:••:’>.  v;  . j.j,  .7'  .J  ' . £>*  :oy,  -i»ij  r.  t.'i  ;ji.7,j.  - i j.,  r 

•-ei.il!>  v'.rvl^* . ,^-.f \ ; i flrrj.<?7  'xtu  ••.  :'f*  IjDi^oI^v 

■:  ' 0-  ! i ui-i  »j;  i 'v*d  *)iV-'  X*iOr>  •'  ’lo  a -'id  J.i*» 

■-■-  •'  -■-  ••  •,  i.r  JuaTio  j » j 

,-57Mr>  I,j''v':  •••.  :■;  C-'.  \ yji  ',.'rt  1 1 ■-!  I :jo  1 . j.i:  j ,:  .'.^y  £il 

- d wj;..l7  : .*£.i..-  j.-,r  > .i.rxe'Vw.'f  OJ  i7r3  -;\;L*i.x. , J.i?; 

'M“7r-yl:fo  i-r?  r-  a>'  ;c>;.:!  'rj  .roifiV  xxoi.?oi/o<i'i  *r..i 

f 

d.-.l  1 si.,u43  T'i;?)y  t'Tcy  Kj  J"  1 X:  ■ y r.:  bo/‘:j,'/^ 

..  - 't'. e";r  Xq  'iy  nolJ  o.-a r.l  iis  ’ClJtioo 

. . : - rfn ‘s.~-'-..,vn- 7. 

o^*.?  .*^oli(x;j  kI  'xuIIj.'  o.i  . :;'*o  -.'i.'j  ^ Jl  • 

• .'?  r;.;.';.:,  .'  -d.iaiXo  til  -.>\r  , -y  anco -iX  JC3  : . ..  f . 7 

* • ’ ^ *"  ' • - 

r;-7  \u.'^.'ior  vl’X  jqo'i  T s’locx  a*i.a'*ioq  'I  o i' " • c . 

. -■  .p-  . . . yXoX'Ico 


. r ( 


p Knit  ► j..'  X i o '■'*  f ^»*t -"'V -I.  nL’-^ 


35 

The  microscopic  pyrite^  in  coal  consists  of  minute  parti- 
cles rou^ly  globular  in  shape  varying  in  diameter  from  a few 
microns  to  a hundred  microns. 

The  proportion  of  the  total  sulfur  that  is  in  organic 
combination  varies  widely  in  different  coals^  althou^  in  any  given 
coal  the  organic  sulfur  is  much  more  uniformly  distributed  through 
the  coal  substance  than  is  the  pyritic  sulfur.  ^ The  organic  sulfur 
of  some  coals  is  sufficiently  hi^  to  limit  seriously  the  extent  to 
which  these  coals  can  be  cleaned  of  sulfur  by  washing. 

As  a result  no  doubt  of  the  deposition  of  fine  sediinent 
in  the  coal  forming  swamps,  contemporaenously  with  the  accumulation 
of  vegetable  matter,  coal  contains  more  or  less  fine  clayey  mater- 
ial distributed  all  throu^  it.  Dr,  Reinhardt  Thiessen^,  micro- 
scopist  of  the  Bureau  of  Mines,  says  that  microscopic  examination 
shows  all  bituminous  coal  to  contain  very  fine  ash  particles  proba- 
bly colloidal  in  size.  Plant  accumulations  deposited  in  still 
clear  water  would  presumably  form  coal  containing  none  of  the  in- 
grained clayey  ash,  but  only  the  mineral  matter  of  the  plants  them- 
selves. Other  layers  of  the  bed,  however,  which  may  have  been  de- 
posited during  a period  when  conditions  in  the  swamp  were  different 
and  slimy  mud  became  mixed  with  the  organic  raa,tter,  contain  varying 
proportions  of  clay. 


^Theissen;  Occurrence  and  origin  of  finely  disseminated 
sulfur  compounds  in  coal  A I M E Bull,  153,  Sept.  1919, 

Iwasaki;  A Fundamental  Study  of  Japanese  Coals,  Technical 
Report  No,  2,  Tohoku  Imperial  University, 

^Dis tribution  of  the  forms  of  Sulfur  in  the  coal  bed, 

Yancy  & Fraser, 

^Personal  communication. 


- V ..i ; I-  :,x  ^ r>iQOOQc-C',  { r;  .>ftt 

/* 

; wi  I-*',  . i : IxTir-.  t*..:  ' •'H'xii-i.  ol;r,  e.ol' 

, od  .'  , 

• fa'i  'J  ■ ..'u:  * ic  r.ci Ji c-  r.-iT  ' . J 

rvri%  :u  f .*■  : i':?  ni  j ^ 

-.QL'ot  i)--’ i/Ji- . '-iZ'Uci.tJ  r : e.:;  :'0i  t 5»i  oi'/iij:  ' 5 UTftOo 

'ii;':Ik;o  '•  ' . ''If'  ai^* Itv-  .•  .,*  •;•;  rr.ifiS  fr.  v.  i^GO 

c4  J . ; " "/.  r<-z!i^Lf,c  , zr.x  ‘ i' : t.!  o£a  : i.  ; 

. . 'rlflA.  ’•■  I'-'' 1-ia  '.■’fi.jftra  O'^  vf«»o  ai  • .•*■  . -lol/tw 

f 

■••  t' -|J  io  J-QiJO  > ; r j 


'jha  : 


L: 


MO  ' 


:■  OrJ  Twii  ' jJL>i  .-.i 


.X. 


d3  ■ ' A ■<-  ' 


V ^ ^ » 


^ . c- ' ‘ ~ 


.:i’l  s*  . J 


r.^L iJi.  , ’’.i 


\. 


r.  i .1 


o'-ri  "‘.U-'oauo*:  Xlx:.  q\  ' ‘ , if.-: 


v^S*  ij 


1-  : J I'i.  - v'.;  '■  wl  .O  ’CU  UJ  1 .00  XI vj. 


* • k-#  ^ ‘ ^ ^ I . ' 0 W jS  .'i  — % 

- j >.:;  I.;  ^.*:oA  . I 'Jiv,:.  cacl  •';I  i..r 


X.  ^-XiSXX  Oo  V -i-  »-  j j! 


'.(T  X'XOl.  v I'-'O  C>7r  'Id-.ili/  »{ 

• ' ' *W  i| 


. ; 1 


•)I:‘  I.  '1: 


; 'J  ">  . <; 


M ' ^ 


; O '.  "I'-v 

I vow 


V , .►A  • JCS.U  X>9nJtiiT::  _|fj 

-.to  ■ 'TOi'.rO  ,ct>vXoa'^S 

I ,'j  ' 


It?-';'':';!  ' i^r*.  r.  vaJ.iJi  L.;;oii a- ‘.'xao  ..•a;'--  O'OA'.f'q  c ^;;:X'i;if:  IjiiJ’-.u vC 


i 

•,;!  V -;i;c^^ao^'  ■:  0 ^ c.'f^  .U  It:  ©uijt-oori  •^r-I  T 


Lj  1.  aaox j“ip{jc*t : 


I'}it<’  i;...;  a ••  lai/^oO  ;.:©<?« in ffT*^  ^ i; 

, . i .rrca  :il  V.  r k X .00  >jfccufO<p^-  'i-''Urn  ^ 

. To  ybk^Xli  A I 


.'■.  ' ri-.-TinU  ii.'j.  c' 


■:o(TOh 


• I _yo  p;{J  I i MUTI  f. . 'I  r:  I '-  ;:cxX'a^  ' aiC 

« 

Atfco  Xb;; 


■„V,Gr;j?Y  ■ ii , 

••■iT 


1 


36 

As  would  appear  logical  in  view  of  Thiessen*s  definitions 
of  bright  and  dull  coal,  the  dull  coal,  being  a heterogeneous  ac- 
cvcnulation  of  plant  degradation  products  in  a finely  divided  state, 
contains  as  a rule  more  of  this  ingrained  ash  than  the  bright  coal, 
which  represents  larger  woody  fragments  in  their  entirety.  Nebel^ 
made  ash  determinations  on  a number  of  samples  of  bright  coal  and 
dull  coal  from  Illinois  seams  and  in  every  case  found  the  dull  coal 
to  contain  more  ash  than  the  bright  coal  layers  of  the  same  seam. 

Coal  m.ay  contain  a considerable  percentage  of  ash  in  this 
form  without  showing  any  appreciable  difference  in  appearance  from 
clean  coal.  One  coal  from  the  Pond  Creek  field  in  Kentucky,  which 
was  examined  as  to  washability  contained  34  per  cent  ash,  practical- 
ly all  in  the  form  of  fine  clay  disseminated  through  the  coal,  there 
being  little  or  no  visible  segregated  impurity.  Coal  which  contains 
an  unusual  amount  of  ash  in  this  form  is  sli^tly  gray  in  color  and 
lacks  the  luster  of  purer  coal.  V/hen  it  occurs  as  a separate  layer 
or  bench  in  a seam  of  clean  coal,  it  is  comparatively  easily  dis- 
tinguishable by  the  contrast.  Such  coal  is  called  bone  or  boney 
coal.  Considering  the  way  in  which  coal  was  formed  it  is  logical 
to  assume  that  there  might  be  deposited  mixtures  of  fine  mud  and 
vegetable  attritus  in  all  proportions  grading  from  the  clean  coal 
on  one  extreme  to  pure  shale  on  the  other,  and  it  is  probable  that 
samples  representing  such  a series  mi^t  be  collected.  Those  sam- 
oles  in  the  series  which  contain  too  much  ash  to  be  of  any  fuel 
value  would  be  called  carbonaceous  shale,  ■which  belongs  in  the 
other  group  with  the  segregated  impurities.  There  is  no  definite 


^University  of  Illinois  Sngineering  Exp.  Sta.  Bull.  89. 


1:!  Oy 


■yi 


0! 


' - r-  • •■ 

, .,  r<  ^ oi-J  , c’,^  .t  *tQ 

•1)1'/ i'./  V,"'j;;n  ••  iTi  tiu  ■'  il-.  lJ  \ ' y *h  .m’'*  )L’3;D 

« i ■■  •:  .'J  rs^'w  ri'm  ; ,.  ..X  'i  oa  & / sn^:iiic:.< 

. . yl  •.^.r;.o  -iof:.,-' 

:>  X r:'-.  * r;  ( ..'‘tiuk  ic  ■•  X.  • :n'i  ?,fOli/sixiari  t“5^  .XT  '*. 

11;;  • •>.'^1  .'>r*.yc  :' , 5 , - - . rrJ:'  b 8.tl9-v  ’<or*£,l  mci . l"oo 

<iu  cys  '‘i-'v-I  X rfe^s  (S’-”  : uljjXrrco  oX, 

i’i  i-'r  >,  'i  V rt\.  3"neo'xr^'  3f . : i.^xtos  « riT]' Y^sjt  ' »\  • 

'!.-  't*  .*n>'  .:  ■;.  :)X.- •: .. \.a*  .; 

» * 

, , i:  ..:  ~X  ' -ao^  ■)  ' * .♦^‘■•■'X ' £aac  *>jt  . O'j  ;v.-elo 

r ■?, 

02•x^^  , . X .)  . ' V . ‘ •XjX  joo  "c*'  V i ^ cX  ci  / . v . 


t 

uv  - '1  on  ." 

. ' J V - . ^ 

G.,ej[  ' '1-^0  • 'Jo  *m<  ■. 

*iX  Lie,  ■ ,1 

i ■• 

'■'.ij.  • X-jOw  . ' 

c 

II-  ' 

VI;  3 4 9.r<fi'UV  0.;  T 

six  XII  snii; 

wl-.  o ni’.;.;  .i  ■'!■."'*  J a.jon.-p  1 ‘.rouai 

■ nJ  . \ VI  ; 'il.-  J-  ^ fijio  si 

0 X~‘  i:'.  :.o  v’. :-r.  i J^«*i-  ;T:,;or.'  ■' i , '';>  j-iv-,...  ,;  to  ; ^ *';£  .'O/jsj  'X  0- 

' c>_~i  \ O'-  ^ --i  */yi— A «; jL  1 00  a 'wiiw ^ • **  k J G 0 X t 


i : v.i  ^ ’ 

Xi  ';'•  v'l 

U..-T  I .0X1  r::2.i\'  r.l  vrix  *.■  X 

. 3->cU 

. 1^0  0 

< ^ ' a ■ 

x:  ‘ic  ;s:*2  .; 

-iai  ooJlr*Qq-:^  d~-'  f/ysD. 

^ b‘44v  Ol  i C i 

Cj  .*T  i.-:.f  0 

01 IX.  xic'iX  ■ 

GaoT’-'  XT...  ill  •e;:.; 

> '<•  r * .-  » ' 

«►  s»v*  ^ * 1*  . — 

r .j-s;a©  v 

Sjug"  ‘iJ 

u ax,  Xi  h: 

■ > , .*  = 1 >-■  ;;  X -10  ototi'-'- 

vss'iX:-s  cnco  nc 

. Cit  j;ri'  .',  o,J- jof  I ■:  G o-v  X cuk’xK'  a-  rfp^i/fe  saX-  • ->-3^  - * ii:  p-ol.ifiiii- 

yi:  o.^  dv,v  cio'JiH  ooi  rXx.XncG  •.'•'pi:f'y  Rni  .vs  .'t  X .\i  \^oIg 

i . 

0,'L  ....  svaulG..  rtoi,'  , '.is,  ijf 1 1 •...•;  ■ »itX«y 

r .i  bO-o  oa  ol  on  - • it  i«V<5jj,U  1 o ori.'  ciuo':..  '.'.oax  o 

. . * . .1  j-nX"!  aioifil'i  xo  :..  ~ 


37 

natural  dividing  line  between  dull  coal  and  bone  coal  or  between 
bone  coal  and  carbonaceous  shale.  Probably  the  most  satisfactory 
arbitrary  classification  would  be  to  designate  coal  of  the  debris 
structure, which  is  clean  enou^  to  include  in  the  first  class  sal- 
able coal,  say  up  to  12  per  cent  ash,  as  dull  coal.  Coal, which  is 
too  hi^  in  ash  to  include  in  the  regular  marketed  grade  of  coal 
and  yet  too  good  to  throw  away,  mi^t  be  classed  as  bone  coal,  and 
that  which  is  dirty  enou^  to  be  discarded  without  question  may  be 
designated  as  carbonaceous  shale.  The  all  important  characteristic 
of  this  series  of  impurities  is  that  the  ash  is  very  finely  divided 
and  inseparably  mixed  with  the  combustible  material.  This  is  well 
shown  by  the  results  of  some  cleaning  tests  made  on  the  Pond  Creek 
coal  mentioned  above  using  the  Trent  process  of  oil  coagulation. 

This  process  consists  essentially  in  grinding  the  coal  in  water  to 
about  200  mesh  size  and  then  agitating  y/ith  half  as  much  by  weight 
of  crude  oil  as  coal  until  the  oil  and  coal  coagulate  in  a semi- 
solid mass  rejecting  the  water,  yihich  carries  in  suspension  the 
free  detached  earthy  particles  of  the  coal. 

Tests  on  the  Pond  Creek  coal,  which  was  of  the  boney  type, 
gave  almost  completely  negative  results,  the  water  which  separated 
out  on  several  washings  of  the  same  sample  carrying  altogether  less 
than  one  per  cent  of  the  total  ash  in  the  coal.  This  would  indi- 
cate that  even  when  almost  all  the  coal  is  crushed  to  minus  200 
mesh  size  the  ash  particles  are  still  included  in  or  attaclied  to 
particles  of  coal. 

The  other  important  source  of  inherent  ash  in  coal  is  the 
mineral  matter  in  the  original  plants.  Wood  in  its  normal  state 
contains  on  an  average  about  one  per  cent  ash;  but  since  the  plant 


- 




P.  ;?■  - -I  J\-.  :\  ;•»-  .'  ♦ vO;:jD;5.n  . v.’o  blu^  '‘i  - .'  ^noii 

^ , St  ::;.  .:-  •-  .■.•  ‘^o  I:iCO  9- ^i^.^  la<?*o  OJ  ’'J  Mtfo;v  ii  rjelo  , ' i ' l<Sr.fu 

I - 1.  »j  'I;'  ri  obcic*.!  aJ  u>  : I-j  -.i  ’ ” < *•:.•. 

I c:i  Ciu:  - , ~-0  . ' a , .-■  •r~''  , . ; a. 

-■ilt  ill  a^I^Loat  qS  lf^*=r>  f.I  ’^1'; 

\ 

•■•-r  ..  i , r. . v:b\r!.)  OJ  .cjO*J  ^o3 

‘ • \ 

av  , x<T  aoi^  ■-)*.,>  i j - i*'  bfib  vJ  c^'.<qffa  \'iiO  ai 

: .'y  j :i>J  . zrj^.}  LIji  OtC.  . ir'^'^iiciojynad'ij-o  */ 

/ . 

oy.Ti.ri:->  r ,/i -*'■<-  ui  :fr  ; ^ r- .>  .i'j.y.  i 1o  9l'>!  i ■■ 

'yr. 

il'-r  r'x  .:;i?':'.  . i.>'}  Xiv  a.'1#r:p:  > of)xii.i  v.::>a  •q.'i'r.l 

: ':-.j  ,:t/-  ;p:\  CijOO  1l 

i?  *'^ 

* tIj  u :jT'  ;oo  £i  c ic.*»o')o->  TtV  9 : i><:i  j ••v  ir-,  Jboccoi.’rtyy: 

|,.c  At  r;j:  i’.o  ' -‘  3.:':.'>;ii^  ni  v:i  ,£>  a^elano.".  ■ 33*»ootq  oii.ij 


>ji 


'J  t'i’.  .T  i!- 


• -c  A 

^.J  , i ,.  ..  .^  VJ 


'■  IX  a>. 


. : 1.  : ■ .if;-?.  ..s:is  rqT  ri  v'yi  -f/Cu. 


.'.-'.ru/  bn-  XJfc.-: 


JLi : 


^ ^ .X. 


t bi/ID  iC 


...J  ltd  :ri  c j.i  i'L  j ;{>.j.l  . , • -i.j’  f ;-v.  j , • -:'b3*i  ®s*.>u  bilv*;. 

. . yr>  or:^  e'.AC  i*  ri.-:;  v.  J*  ,^cr 

■ -V..’  *!.-•  «._.v  / , ' ro‘;  3-*  '•. :>  u?'*?'?  ,.'  u-  , . 

;c>r»a  xoJs?.-  ©i,..  t - yrirqjyc  v. tjJ  y.r,  ; '•.  o -.'’V:';, 

•;3al  ■:  ?•'-■  fl.,  o.i  qtr  ■ n a- vra  ri:".>  » uo  Jjo 

-■  '-•■•  axf^"  . soo  a:I.J  rti  xlei*  XrJw-‘  '».:j  ;;  X.ijp  .}';o  rt/AvX 


,-f 


CCS  a'';:Js3  i*S'iPti;3:o  «i  i o.  ocii  .tnt/'iXs  nc--.  -'  n.'VT  jjjuj.  ao 


•:  -.•  . 1 . .r.  3ti  ji  oin:  I ! i ^ - jy  . ■:  C : 3 i ..*  12L  i\€\S‘.  J • -9. It  i s Jf’jyis 

, oo  lo  a'  riiXxc.q 


fl.'b  X 

i-  iU:.> 

.'  y 0 r ‘J  0 1: 

♦C- 

T ''.rf  '-.:  ..X..  .li. 

boo^ 

1.3 

X AX’!.!  'J 

X v'vi  ; 

:>.  x.vi'X  s^iTo 

38 


remains,  in  the  process  of  coalif ication,  are  subject  to  great  loss- 
es of  organic  matter,  without  a proportionate  loss  in  the  mineral 
part,  the  ash  from  this  source  in  the  coal  may  amount  to  a much 
larger  percentage  than  in  the  original  vegetable  matter. 

The  total  inherent  ash,  of  all  these  forms,  varies  widely 
in  different  coals.  The  Pond  Creek  coal, already  cited  containing 
34  per  cent  ash,  is  probably  a sample  of  about  the  maximum  which 
would  be  designated  commercially  as  coal.  Some  of  the  eastern 
coals  probably  contain  as  low  as  2^  per  cent  of  inherent  ash,  and 
small  fractions  which  contained  less  than  this  have  been  separated 
out  of  coal  samples  by  floating  on  solutions  of  1,20  or  1,25  spe- 
cific gravity^, 

SEGREGATED  IMPURITIES 

This  group  will  be  considered  as  including  all  bodies  of 
impurity  which  are  physically  distinct  and  separate  from  the  coal 
substance.  Carbonaceous  shale  deposits  belong  to  this  category, 
but  because  of  its  relation  to  the  other  substances,  dull  coal  and 
bone  coal  in  the  series  of  clay-coal  mixtures,  it  was  described 
with  them,  A particle  of  carbonaceous  shale  may  be  considered  in 
its  entirety  as  an  impurity  since  it  has  no  fuel  value  and  is  es- 
sentially a shale,  containing,  incidentally  as  an  impurity,  some 
carbon. 

The  principal  impurities  which  occur  in  coal  as  separate, 
distinct  bodies  are  shale,  clay,  pyrite  or  marcasite,  calcite  and 
gypsum.  Broadly  speaking,  they  occur  in  the  raw  coal  in  one  of 

^The  Distribution  of  Mineral  Matter  in  Goal,-  R,  Lessing, 
Colliery  Guardian,  Jan,  28,  1921, 


}^  »<  , • V.  1 ' . i .i/iaciT 

i ' .i  ii;  aooX  o:^  ;.;d  u^-io  :!  ■I'l  ^ :c^-*  , ‘Jii-;  .>ir.‘'.af  . o c ■ 

. ikOiK  ^ c:'  rri. -'-•  . X300  .:i  ^o'.u-o  : * :'t  ria<  o.  ..*  , f . 

. " % j J 'viT  •-•*  i ; 3 g V ' ' ' X r, . . J :.  ] 

t * '•  '' ■ , - • • • 

:>o  ^•’.''  ; .V. • . J.  j _ _ ‘'>'1’.  , q'  t C- 

- J.'O'iii  io  eli;  “c.  & ;Xc'rq  8 , Ififci  v>f. 

18  'I 

, j : 

•*.'  . rt'V*'  nw  ■,.:'i'^ 

. > *cw±#^-?K'  ••T.u  *,nX3jtfS_  : v,X  f-'rfn  ^ 'i?  . J’:?c 


.CtiOO  a:i  \;J i .•.•'t- i biuo^ 

■ 3T  *.*:f'f!  iiC:  ar  wcl  Ui.  r ii^.i  v.' 


I -■- 


o^lii'lU-i-wX  'jaLTAC;«:’XL<"3 

^ S Lb  5 oii  n.j  t •>'- st.  •’ oo  £ ' ILin  *Wi.-TC->  ^irfi' 

* - ?)f:^  /cni;  "•iw  vI.' -jc  T"*! 

t ♦ 

XoO  ;■;  •:»'i..'';»'  i3  i.  jr.  : ''£>  mXa  ?;■  ;;  v : •:•  .,:o  JnC  . J r ii 

!3f-  ' • ' 

:vv  Lltj')  , ..  1 . i • •,  ■•riJ  03  »3X  ,-.Bw«aod  t.U'^ 

bv •"'i': . io: ' » -a*?  , - v'l.--' ? ? Jt^  .’.  ‘lo  g.  J ;:i  Xi;C»a  onJb 

■ ■'  "■  /I 

o ‘ J«0804»nuuifi0  Iv  gIo^iJ*rr^.  a ‘ ’ 

..I  . •.  : ;s  L-  v j'l  c.  c.i^J  -^3 i't ifq.it i **-i  j;  ’i3or*i..';i0  e ;.. 

, ‘ • L .::  :i  \ vi.C  i^naX  ^ g:_  : , «iir.i.<3;.  ,Gi^r(g  rj 

■ - . - ' ,.  . -gr 

,1 

■.'■  ••'  " •••>  i 'C'/  n;  7Uipr  .'-.i  X6q!?nl*r' 

' ." 

■'  ■ -i  >•;  ni.  liioo  •■’ij'-:.  '>o3  qi  i»/g.oc  vp^:’  ■ ci^i  . Jtjiri;; 


,H  - 


1:3.- 


1.-:  . ■ 11  . ; ' .toi  3 


•—  ^ rs*.\. 


, g^•rTr.r{^ 


39 


three  physical  forms,  namely,  as  layers  deposited  "between  the  tench- 
es of  coal  in  the  "bed,  as  infiltrations  deposited  in  crevices  in 
the  bed  subsequent  to  its  formation,  or  as  extraneous  impurities, 
usually  from  the  roof  or  floor,  introduced  during  mining. 

Shale  generally  occurs  as  layers  interbedded  with  the 
coal.  Pyrite  also  occurs  in  this  form.  In  the  Illinois  No.  6 coal 
a continuous  sheet  of  mineral  matter  called  the  blue  band  is  usual- 
ly shale;  but  in  some  places  it  is  pyrite,  and  in  other  places 
shale  and  pyrite  mixed.  These  layers  appear  in  a vertical  face  of 
coal  in  the  mine  as  continuous  horizontal  bands  and  for  this  rea- 
son they  are  called  shale  or  pyrite  bands.  Those  which  separate 
easily  from  the  coal  are  called  partings  and  those  which  stick  fast 
to  the  coal  are  usually  called  binders  althou^  the  two  terms  are 
often  used  indiscriminately.  The  bands  vary  in  thickness  from  al- 
most nothing  up  to  a sufficient  thickness  to  divide  the  coal  into 
two  separate  beds.  Those  which  are  as  much  as  half  an  inch  in 
thickness  are  partially  removed  by  the  miner  if  they  are  firm 
enough  to  withstand  shattering  during  mining.  The  thinner  bands 
and  small  fragments  of  the  larger  bands  are  mixed  too  thoroughly 
throu^  the  broken  coal  to  be  removed  by  hand.  The  washability  of 
the  coal  depends  in  a large  measure  on  the  physical  characteris- 
tics of  the  shale  bands.  Where  most  of  the  ash  of  the  coal  is  in 
the  form  of  numerous  thin  and  friable  layers  of  shale  washing  is 
difficult#  Some  of  the  shales  occurring  interbedded  with  coal 
have  the  property  of  disintegrating  rapidly  in  water  to  form  a soft 
mud.  This  also  causes  great  difficulty. 

The  infiltrations  are  usually  pyrite,  calcite  or  gypsum. 
This  is  the  typical  form  for  the  latter  two  m.inerals  and  probably 


v -*  : .‘sout  1 fc  aco*'-  Ciioy.^-f  * , ' I , ' ■ z.  t , 

I nr  .'1  i-iti"  ir;.  4-b  onoi".t  oiw  XiTn  ? ■;  , jcJ  ni^i-oo  ;>  t’c 

^ Si-,  -nx'.;?-.-.:,  ^ 9c"r 

, tuX^v.*io  i'jo*:  ■ •'.  xlX/ti;*!; 

yr 

r.iyouv  vXX:*,i5ev'i  elfixifo  . . 

rXitv’  ;ti  a__;:oo  o~r-  -'iitv.  . ‘ 


iV  5:*0  : ■ 


t*  ~ UiT  A ^ _ X ' ■ .t  i>  I 


'Ik/  Ua  >.. 
c:  ->  0 -I'J  . 


..  (T '.  •'.'i'53  i -‘(.M  ;oXi»ii;i  \;X 

X -i  ix-?  - • '-.i  " >?u.^K  «-^Env-5i  , ■ J -:!r,  z^My,y^q  bn-j  oI*;ris 

' :iAk.-»rf  *ii.i  ‘t..':  j.  X w*  "f  i*Ti  X.oo 

j ^ no  a 


if  a. 


■X  ■■'i  c oi  i v OK  If  .X 

*.r-r*  V io  - 

' J N. 

Xr.^ci  ?'C 

-•  '’  ; . •' ' i .:-w  enoi"' . .') 

. ; ' 1 ■;  : r » 0 

X’ 

XiilOO 

[i  c.Ti't,*',.:  .■  •' 

s If  r.t  ■ 9 IX  • 

\Z.l.  •;'»j 

■'’•••'  ,•■■:  / «l  '.^j;'  ariT  ^ nOw'l' 

Mw"*'!'  r ■.■!'•  0 '’j  c,J  ■ fli  ;■'.■■•.')  i ! iiOi  Ol  t"t  'v3  ,*  c;;  •’:'  Xoc.;' 


'i  i-’‘-JiTi  ••  lf.^rf  • ;'Crjii  ,r.  m;a,.  :l-Xi'1i'  S30?fr''  -.-j:?,.: 'ii..qD«  it-' 


i‘  1 mjI-' 'U  r.'r.Xu  e*.'J 


I'lntix.  X 'ir'y 


•>  -x.^ 


sr.rtoX 


. .‘i  i.A' t>it£^6d^i  ' oj 

V‘Ti5- o.iJ  CO.;  /jsxiri  t m 1 . t> rW  lo  t>:^ ".:  r.rr;: 

•.;.:  i f.  X X-^vi^i-'W  yS  'itJVOai'T  t»J  Oi  Xi*0;j  .'i'XAO'Xj  ''oHX  i^uc'znt 

~ TZ-.J-oj':.-  jc  X30ii:y4,7  ^r-’J  no  dtu’?jt:03*.  ftc'rt=X  •'  aX  a >ne:i  ’ ' X..co  onJ 

i.u  :.  I X ■•;•:,  "lo  risa  *ds  X-,  ioc.'yj  ::‘i.Oi 'V  aln.,.  yA:  lo  80iX 

5nX^jS£-'  ::X  ::fj  ’Xo  -.  c “•;.*£  X)iXr3  r:X-TX  XjoO'i-'  is,4a-  lo  art  j”: 

I j.i  7,ii.i.-ii'v/.voo  a^X^.sia  on.oe.  ,,X^'oiTti^ 

' a Jjjtt  ; ’'to  -:X-. ;.  ' Xv  .■‘‘•iX  o*V..l 

* ■ • -■  ' . X,  -'• 

. •j'voXi  ti^)  nji^D  oalo 

•': -‘C  -X  ’ , 5'i‘£v;cr  •^II jsjx.'rxj  91.8,  ■'inoi J I i’ini  o/fT  /^v' 

XJ  . . .*z,^  ..i;  ; -lA  'C  ' I'  a^v  T"I  I'Cr-  : r.  .‘,:  /.;X  si 


^‘i'-rn  *! 


[I 


40 


the  commonest  method  of  occurrence  of  pyrite.  The  calcite  and 
gypsum  occur  in  the  form  of  thin  flakes  in  the  Joint  cracks  and  on 
the  minor  "bedding  faces  of  the  coal  and  in  very  thin  veinlets  which 
sometimes  give  a lump  of  coal  a crosshatched  appearance.  These 
flakes  and  veinlets  are  very  noticeable  because  of  their  white  col- 
or. Since  they  occur  in  very  thin  brittle  sheets  they  break  up  very 
finely  and  are  for  that  reason  rather  difficult  to  wash  out. 

Pyrite  also  occurs  as  similar  thin  flakes  or  even  thinner 
than  the  calcite,  as  it  sometimes  occurs  as  a mere  film  like  a coat 
of  paint  on  a natural  cleavage  surface  of  the  coal.  This  form  of 
pyrite  is  often  referred  to  as  flake  sulfur  or  float  sulfur.  It  is 
very  common  in  the  Niiinber  6 coal  in  Southern  Illinois,  and  for  that 
reason  the  hi^  sulfur  coal  from  this  seam  is  considered  an  espe- 
cially difficult  coal  to  wash.  It  should  be  pointed  out,  however, 
that  a very  small  percentage  of  sulfur  in  this  form  gives  the  ap- 
pearance of  a.  large  quantity. 

Bodies  of  pyrite  in  a great  variety  of  shapes^  are  found 
deposited  in  coal  beds,  or  in  the  rcof  or  floor.  The  principal 
forms  with  their  common  names  are: 

1.  Rounded  masses  called  nodules  or  balls.  These 

vary  in  size  from  a fraction  of  an  inch  up  to  several  feet 

in  diameter.  The  larger  balls  are  usually  in  the  roof  pro- 
truding down  into  the  coal.  The  smaller  ones  called  nodules 
may  be  completely  imbedded  in  the  coal  or  in  clay  or  shale 
partings  in  the  bed. 

2.  Lenses,  round  or  oval  in  plan  and  lenticular  in 

section  varying  in  size  up  to  tv/o  or  three  feet  thick  and 
several  hundred  feet  in  greatest  lateral  dimension.  The  com- 
monest size  in  Illinois  coals  is  probably  about  one  and  a 
half  or  two  inches  thick  by  a foot  across.  They  are  some- 

^Distribution  of  the  Porms  of  Sulfur  in  the  Coal  Bed,  - 

Yancey  and  Fraser. 


■ '.'  '■  -•  !>»;•..  :■?  C'  •' 

jinoh  ?rj  I'l,  {f'joo 

.,i-  S:u'  f ,’1,  N’t:  'i- 

' .•.:■?■?->••'>.  i,ni'  : ...iX.TacL* 

1 

'■  ■:w\_..-'oo‘': ' r-  I?  oo 

ho  (fnu/I  y tX’'  l; 

* 3 !’/  ’’-:o  02 

I'Ou  '^.=.  .>  .92  i 7 n't  \X'^OV 

f' -'a .. fj.T'  . 

;7  yv*N».  ., 

-J:  . •:  ■ '.  'lov 

ni  *:  fDoo  <“"*1.. 

, . ..  . r t -.j,- y vlfl, 

S .T'  \ ti  't'J  iliiU  i r -•  y.i'jOv  ;..  . ■ o* I'T*.'’!  . . 


j-uyp  ^ ’-Ji 

'i^  Tlrft 

. * * 

O ^ X.  r 

♦ •rc'l  • 


■ y 9TVQDC  Jl  ^ ..J  , 

ACoi*  ■ ■ ; ;-/->^3Xv'  - n;:' tV  V . j(j.  1. 

, * OJ  t©tf9'le*i  u--;i5o  r.  i 


f'  Hi  I 


qS  i .Cv.  'if-'Ji'jtrTI  *uJ  /u  fio/.taoo  ^i'^■’V  ji 


AL  .'JC  .’  ’'  + y 


. •v.l 


- s.  J ^cv  ^ 


1 '1 


-•  M rc'  ft  i X 


lr<? 


lo 


I -00  ‘X'..'':f.'>::i 

i:.:? 

1*; 

oj  x,.j. 

tir> 

. 7 i:7'0",C  LL.',t&& 

1 - X » 

<1 

.».  i , 1 

-*  i - ^ ■ 

CO-  0 0 

i.-;-,  ‘^edo'JU^e  i L ;*^v  ‘ 


. :i‘:^q  Ic-  *»f, .tJ03 


la;//.. 

0 , 

* ■*  . • 'I 

:ooi 

t> . y ill  It 

( • ' 

Xac;  ni  X>oJi©o',, 

■- 

ao.; 

a 01  ;.“.Q'.;' 

nio^r.i  a'J  i , c '^'ro 

• - • - « 

■ -^yJ  10 

«3  si  nib  on 

.05  U ■■ 

* ’•  '(£,  ' 

y ■ ' ■ . . -;  ■ 

TT  , - , , * 

W 

■;  11  rf • i 

. -i  '' 

..'uiJoa'ii  ,*. 

all 

^IJ 

”*  '.'1  '1.  L 'l 

-r'.J  ni 

1^1 1 ./m  n 

3‘£  ' 

■ f 'r‘.)>i/C'l' 

£.'"  on  o ■ 

' I.:d""co. 

"» - > »a  ^ f ■ T ' 

• ♦ </  k • ».  » xA^k^  V Vl 

O^Jli 

Mw'oc  0 ;Xbti*r/'  . 

0.  '.  vu.  ‘X  I 

\^..-^'X  0 a, 

X '10  iaoO  OUw* 

..«» f* r\ /Arffl*  {■ 

'i.l!j»«Xijabo  > vJss.  ; ■ 

** 

- oiif 

ni  HI.  .li  tiBff 
«•  * </ 

...'  V. 

•oC  jbrta 

r.4lA  ai 

!•  ,0  1 

0 : 

y O.fOj. 

y 

. *o.l^..3:nj:  j J r:o*t7'  :i 


.-  lai  ' ->/  n i}o^a 

y _ 'j’i  Isa'^vsf^ 


V - *.Ws-  *.  . 'J  4.  U PkK^  i * ' H- 

; 'o  u<jo-To  '^.X  .f  CIO  ftj  rL’:oj  ..  f ■ji-l.Cl  X .;i  •"‘"i-i  ia®;iiCJi  .--  i 

‘ vTOl  rf]  .itijii-'.j  C-;';!y,-ii  CV^-t-  io 


oX'  .1. 


M'lXfo  ho  lo  :i  ' 'I.-;  • -c  ^ 


41 

times  called  kidney  sulfur.  Another  form  much  less  common 
than  the  lense  is  similarly  circular  in  plan,  tut  annular  or 
ringshaped  in  cross  section. 

3.  Vertical  or  inclined  veins  in  fissures  in  the 
coal  bed.  These  are  common  in  the  Number  5 coal  in  the 
Springfield  district,  where  they  are  sometimes  as  much  as 
four  inches  thick.  The  miners  cs.ll  this  form  spar  sulfur. 

4.  Small  discontinuous  veinlets  of  pyrite,  a number 
of  which  sometimes  appear  rou^ly  to  radiate  from  a common 
center  v/hich  may  be  a small  sulfur  ball.  Such  a group  of 
veinlets  is  commonly  called  a cat  face.  In  some  districts 
this  name  is  applied  to  the  pyrite  deposits  of  lenticular 
shape. 

The  spar  sulfur  and  the  veinlets  of  pyrite  are  usually 
more  friable  than  the  lenses,  balls  and  thick  bands  and  consequent- 
ly these  forms  of  sulfur  are  not  as  completely  removable  by  washing. 
The  structure  of  this  kind  of  pyrite  appears  to  be,  in  most  cases, 
rather  shelly  or  cellular,  as  thou^  the  deposit  were  made  up  of 
flat,  thin  plates  laid  together  with  spaces  intervening. 

Another  physical  characteristic,  which  is  of  importance 
in  coal  washing, is  evidenced  by  some  types  of  shale  and  pyrite 
bands  which  are  called  binders.  V.Tiile  those  bands, which  are  called 
partings, usually  separate  easily  and  cleanly  from  the  adjoining 
coal  at  a definite  boundary,  the  binders  often  merge  almost  indis- 
tinguishably  into  the  coal  above  and  below,  so  that  they  will  not 
break  apart  as  clean  shale  or  pyrite  and  clean  coal.  The  band  of 
impurity  in  such  a case  is  usually  made  up  of  a layer  in  the  center 
of  comparatively  pure  shale  or  pyrite  v;ith  thin,  parallel  inter- 
laminated  bands  of  coal  and  shale  or  pyrite  on  each  side,  v/hich 
gradually  change  to  coal  farther  from  the  middle  of  the  band. 

In  coal  beds, which  have  a soft  floor  or  roof  which  swells, 
the  vertical  fissures  are  sometimes  filled  with  clay  veins  forced 
in  from  the  floor  or  roof  by  the  pressure  of  the  overlying  strata. 


42 


This  is  one  source  of  the  clay  in  coal  which,  due  to  its  fineness, 
malces  trouble  in  washing  eind  indewatering  the  resulting  slime. 

The  other  source  of  fine  clay  in  coal, aside  from  such 
veins  and  occasional  soft  shale  bands  which  disintegrate  in  water, 
is  the  floor.  V/hile  some  coal  beds  do  not  have  a clay  floor  most 
beds  have,  and  some  of  it  may  become  mixed  with  the  coal  due  to 
careless  shoveling  or  to  undercutting  in  the  clay  in  place  of  in 
the  coal. 

Particles  of  shale  and  rock  are  also  introduced  into  the 
coal  from  the  roof.  The  amount  of  dirt  going  into  the  coal  from 
this  source  varies  widely  in  different  mines,  as  some  beds  of  coal 
are  immediately  overlain  by  solid  limestone  or  sandstone  which 
does  not  break  up  at  all,  while  others  have  a roof  of  friable 
shale,  which  is  shattered  somewhat  by  the  blasting  and  pieces  fall 
into  the  coal.  Some  shale  roofs,  which  stand  up  well  temporarily, 
begin  to  disintegrate  rapidly  on  exposure  to  the  air  so  that  pieces 
scale  off  and  become  mixed  with  the  small  coal.  Probably  at  a 
great  many  mines  the  quality  of  the  coal  could  be  greatly  improved 
by  careful  mining  to  eliminate  dirt  introduced  by  undercutting  in 
the  floor,  shooting  holes  that  pick  up  clay  from  the  floor,  e.nd 
shoveling  up  clay  with  the  coal.  This  is  one  of  the  most  difficult 
free  impurities  to  remove  by  washing. 


< " , ' f'-r  i-oo  a-  fo  -vrij’  '^  / ei'iuc  . ■*'  , .j  rtl*{t 

* -ailc  ';:^*T  cTi.i  :,  li’toi  ; v,io.ri  ■.*!-.  r:i 

.tOi/e  C)'*  ■ »!)i  , ,,?U0  Ili  1,0  owll  i .*  ’3„‘S.iJD’'.  'J,«fIlo  OJ  ' 

, .1:  ;v*ir(;«r  zbv.zd  oliina  Xi  ; aWleV 

.r  U-;  -'.  oX^  vela  ev-n  j , opl’t  o.-f^ 

o;^  ■•  Ik' 00  r>r{;!t  ‘ . •■  .^r  .uo  •'';  i x >.;  Si  ?o  oirua  ,; -«*  ^ .-.»r 

-.‘  1c.Q'j.J.i  ill  \i-.Sc:  3.’J  v.iij^vo'3;>ony'  yX  *io  ^::iX9V0rCj  «ruI  - : ;. 

*>  ' • . 

"r  ' ■--  • .,  *._'  • ‘‘00  -niS 

. o;':  .>..*  cal  j o't  5 -jt’oo'i  J&rt-.  » C-gac  ' '“•.e  3.9.  v - ; 

..:.;co  o .:  oiri.  inti  a /.:e/0i3...i  ^/T  /V;;  .>*1  dftt  :01c  XnO: 

.I-'-o.-!  _'.  r:jf>.,  .v3G/i.-^  , ‘J.uat  / ,.  '':oi’* j ;;i  \^Ze'jx4  mxir.  r oozii'ja 

«..>x  -r  j 7-  ®r-'::'  X.  b.fi.CB  .‘X,oX%'^vo  “TiTc 

:5  -;.>Xli  lo  tOO*I  -,  G xil  - , . :.  ^ <*»;  ..■f.ottf  jca  .tJOoi) 

'■'  ’ r.oooiq  j.T '.  :,nX*n:rXc;'  ooj  - i;.i8  ai,  uoi.rftr  , <3-:.  ip. 

'<  j.XoT  qtr  X>.r  Jr  . •t'-jo-.i  aX..,r:.#  * ' ••co  Cifi  ' o5ni 

t>  :S  'jS  O’! ,;!? O'.tx’R  . :o  v£L'!if;.’’j  t j oJ 

- ’■  ■-  ' 'rj.  Scdox  . ,0  » ■+  4U  / 00  vi.:  f^.,-'0o.?!  • 

. « / 

-',. X ;j  j :it.'0'i  Z-’,t>0  jrUt  i k,  \Xixjui;'  oO  * 00*0X01  V.';  '.j^  J/jO'C,- 

..X  . ,..i»  u Jo*i  ;o -X> '.oi.l  ai  S'lib  uX^^rtiiiriX o cJ  p...?  -i.Tt  late*'!  iO  ‘j- 

T'C'Ct  X*‘Xo  fJIT  J .^rij  aoXor.  ^/iiiOOflf'  ,-ooX'i  orf> 

X--ol’'':'ij  .“a 4.;. a o.Xj  'io  ,r.-,v  >a.i 


::  X S'.  4. 


on  On-,.  fL- xw;  ',*j^Xo  r-nXlRVOuX: 


oi  iir: ,« V J 9*/  om»>',£ 


0 J i S 'luq.zL  vO-0T 


43 


CHAPTER  III 

FUNDAMENTAL  PRINCIPLES  OF  COAL  WASHING 

7.  Effect  of  Differences  in  Specific  Gravity*  It  has  al- 
ready been  pointed  out  in  the  introduction  that  the  commonly  used 
methods  of  washing  coal  separate  the  coal  and  the  dirt  by  taking 
advantage  of  their  difference  in  specific  gravity.  The  simplest 
operation  which  illustrates  the  underlying  principle  of  the  process 
is  the  fall  of  particles  through  still  v/ater.  If  a number  of  par- 
ticles of  the  same  size  and  shape,  but  different  specific  gravities, 
are  dropped  together  into  a vessel  of  still  water  the  heavier  par- 
ticles vfill  be  accelerated  more  rapidly  and  attain  a hi^er  limit- 
ing velocity  than  the  lighter  particles.  Therefore,  the  material, 
v;hen  it  comes  to  rest  on  the  bottom  of  the  vessel,  will  be  strati- 
fied according  to  specific  gravity,  the  lieavier  particles  being  in 
a layer  on  the  bottom  with  layers  of  successively  lighter  particles 
above.  One  of  the  early  washers  invented  by  M.  J.  B.  Marsaut^  for 
cleaning  coal  at  the  Besseges  Colliery  in  France  makes  use  of  this 
simple  principle  of  a free  fall  throu^  a great  depth  of  still 
water  by  dropping  a charge  of  raw  coal  into  a tank  of  water  twenty- 
four  feet  in  depth  and  removing  separately  the  layers  of  coal  and 
refuse  deposited  on  a cage  at  the  bottom  of  the  tank. 

The  rate  at  v^hich  a particle  will  fall  through  still 
water  depends  upon  its  specific  gravity,  its  size  and  its  shape. 

Air  bubbles  attached  to  the  particle  may  also  affect  its  rate  of 
fall.  Other  conditions  being  equal  a large  particle  falls  faster 

^Etude  sur  le  lavage  de  la  homille  aut  mines  de  Besseges. - 
Bull.  Societe  Industrie  Minerals,  Vol.  VIII,  p.  387. 


• . . > '•  , .4  ■ - . 

'j.T.  . ■ I . •'  ■ r.j  r ' *•  *'  : , ■ ■ 

"li)  oCql;  ..  ■ ’ ■•  :•  ■ ..cl:.', 

I'n  I . ■•■:  '.S  . o \ I 

^...  ■ . u ..  . : -■  ;.:  . ^ ‘ 

‘ ^ J V ■ ■ ' t " , , • J*  ' V Srt  ’ ) ,i  i.  ' 

4'.  ' ■ ^ 4 ^ ‘ ’ _ * ■ ' ••,  * 154*  “ 

o’»e'^V  .,  . -^V'  ■ = ••  ■'•  ■ ’•*  • 

• ••  : V / ^ J.  . . ^ 0'' 


1 O 


r> 


i 


. 'I  / 


/i 


• j . 


■ I 


I 


1 


- J ct  • - •■>  V .. 


:-1  < i 


. j .i 


44 


than  a small  particle;  a particle  of  high  specific  gravity  falls 
faster  than  one  of  low  specific  gravity  and  of  particles  which  Just 
pass  through  the  same  screen,  the  round  grains  fall  faster  than  the 
long  narrow  grains  and  these  fall  faster  than  thin  flat  grains. 
Density  and  size  also  affect  the  rate  of  acceleration  of  the  parti- 
cles while  they  are  attaining  their  final  velocities.  Of  two  par- 
ticles,which  ultimately  attain  the  same  limiting  velocity,  the  small 
heavy  particle  reaches  its  full  velocity  more  quickly  than  a larger 
particle  of  lower  specific  gravity. 

Several  text  hooks  on  ore  dressing  give  the  derivation  of 
mathematical  expressions  for  the  laws  which  govern  the  fall  of  par- 
ticles in  water.  Herr  Bergrath  von  Rittinger,  the  earliest  author- 
ity on  this  subject,  gives  the  formula: 

(1)  V « C^D  (S-1) 

lIThere  D is  the  diameter  of  the  particle 
S is  its  specific  gravity 
C is  a constant 

This  expression  is  derived  from  the  fundamental  formula 
of  physics  V by  substituting  for  "h"  the  value  of  D (s-l), 

Rittinger  Justifies  this  on  the  assumption  that  the  velocity  of  fall 
of  a unit  cube  is  equal  to  the  velocity  due  to  a head  of  v^rater  of 
unit  cross  section  v/hich  will  support  the  cube.  The  hei^t  of  such 
a head  of  vfater  is  equal  to  the  specific  gravity  (s)  of  the  cube, 
or  when  the  cube  is  falling  in  water  this  becomes  S-l  and  for  a cube 
of  width  "D«,  D(S-l) 

V ss  j/sgh  then  becomes  V =s  yfegD  (S-l) 

Richards^  says  that  Rittinger* s constant  in  Equation 

^Text  Book  of  Ore  Dressing,  p.  264. 


. t.:  L i.Vj.s'i;-  ,,.09'*. 


T|.  ■ 


. ' ■'  ' •;.  ; X’iS.'^  .v  cii 

’Jl 

ox^ioaqa  ,c  o:zq  ■. 

'ifv  r*  -*'  '■j:,i'^.  r.i  *-;  hriinn  •'  , 0‘ * ^ o:iJ  f u.’t.CT 


*'  f 


4 ' ' 


.11  "'x:  , J‘ V.J11:  MiiiW 


n 1 ix-j  'i.jx , Li’o'riBu  t-u  I 


■ ■'lii:!."  jj'^ 


' .L*  : ••];  or'ij 


I * ‘ 


al  L^:  ' i \l  c .. .-.  'ix  j li  • Jo rts  . i-oi  o J-  J j 

: u £xi1  nSl,  jsdOijfil  >X»;  , ' i ■ ‘ ^ 

,,  VKi:,;  13W»A  ''  5l0i*T''-7 

...  '0  5X0f..  ‘ Xv'.'l'!  v^T...  S^'  ''* 

t>  tmjti  •■•r.o’  , X_..0X.J'3CtDdv'  , : 


- f C.  •-»  t J ^ 


7 


•.t  ■'  ...  •'O'*  i'.*  n:;,-!,* ■{  ■■.'i' 

: . J '-«rt‘x  o"'  U' • 

. ' £-• ) 


''ti-  QOUj.’  ' 'i, 


...ir  -.4'.  .vv  >, 

V;M  V l;..  --iS  , 

C ..Jr  nnv • 


!''rl  J?.r  7*1' 


:■•  ‘i  tfOiaxi  T7 


H ••' 


■i  j":  ' ' ‘ c^^^  VJ  -hl^^zr. 


I 

f ■■■^:r(a  '..fi 


V .i  ‘>w 


...»  t •.' 


> .w'  •:  :i.'  ,*u;.ia..a  o.^'J  ::  i;.I  -i.Xii  «li,. 

■' ' '-■  ■ ■ iou.Cir*  " ."  >..•  .r-.:*8pr  ■ 9i4*jol.  M '■•■^  '.' 

I ^ .h?  > * . 

;-3^yE'tc'  .O' 


V'.}  v^J.  ."  T'.  ai'L  ori*  :•.;  .i 


it''  £:>-*■  •••7  lU 

V-  ■ 


:■,  -’.I ''..''i 


*'  ^ 


\ - 7'.. 


r:or 


r ^ f • . ' t* 

\ ; ■■.  • . •=  >1 


I . -w  J 


■ ..j  :rro;'  •: 


; ' -j  1 r\ 


: >'jL.,..ir>i 


f*' 


'^jx' ; CK.O'j^c'j  A0o-‘  * 


45 


( l)  seems  to  be  made  up  of  f 2g  where  is  a factor  due  to  fric- 
tion. For  large  particles  falling  rapidly  this  fomula  is  checked 
approximately  by  experimental  results.  In  the  fall  of  very  small 
particles  the  effect  of  resistance, due  to  the  viscosity  of  the  liq- 
uid, assumes  greater  importance  than  the  specific  gravity  of  the 
particle  and  the  rate  of  fall  follows  another  law  known  as  the  law 
of  viscous  resistance.  The  formula  as  derived  by  Sir  G.  G.  Stokes^ 
is 

(2)  V =:  K (S-1)I)2 

This  formula,  however,  applies  only  in  the  case  of  very 
small  particles.  Richards^  gives  the  critical  sizes  for  quartz  and 
galena  as  0.20  millimeters  and  0.13  millimeters,  respectively. 

Rossbach^  determined  experimentally  the  falling  velocity 
of  samples  of  an  Illinois  coal  and  of  shale  from  the  same  mine  re- 
cording in  every  case  velocities  lower  than  the  velocities  calcu- 
lated by  Rittenger’s  formula  for  average  particles,  but  the  general 
relation  of  velocity  to  size  of  particles  was  approximately  the 
same  in  the  experimental  results  as  in  the  calculated  results,  that 
is,  when  velocity  of  fall  was  plotted  against  size  of  particles  the 
experimental  curve  and  the  curve  of  calculated  values  were  parallel, 
but  the  experimental  curve  sho7;ed  consistently  lower  velocities. 
Richards^  secured  similar  results  in  experiments  with  anthracite, 

Mathematical  and  Physical  Papers,  1901,  Yol.  III. 

^Text  Book  of  Ore  Dressing,  p.  264. 

3v/ashing  of  Illinois  Coals,  1912  Thesis,  University  of 

Illinois. 

^Development  of  Hindered  Settling  Apparatus,  Trans.  Amer. 
Inst,  Min,  Eng.,  Yol.  41,  p,  396. 


I 


I 


- oJ  ox;'; 

to::  r>  'it 

*<•.  »'  . ...• 

0 1*‘  -■/•i  'i  ' r,  ,•;{.'  • •-. 

'..:■} { t, 

• i ► -7 

i.-  '',  10  ,:  iii  V 

T'  . t T '•* 

73 .1X  X *.  < ■ “^  01*.  • • ' ‘ 1 r. .;  ♦ T 0 1 . 

Xl-.T, 

to  ',  i •'•  O.fJ 

•* 

•1  X.’ivCdraJT' 

.Xxoio.r 

V ' 

1c 

^ • - 

, ■■'  nriu? t ? : 'v:  ': 0 : u r.'^le 

er(u  e*'*.oiJ-i 

V . , . * 1 

vv  X.- 

v.-i.  jiHoSjlj 

O.iv**  1'. 

■ 1 < ■ ■ ’ r. ' t , i Ji  :i^:  :X.  ) 7 

• soyuj^n.^  , 

■*  .a'J  . ■; 

. V.  ,:  lOi'j 

ecu  m 

iZo't  Sl>^1  >0  .. 

iXf.  v.d"  '!  5 

HI 

• flOki  O .-fl’  . ; 

•;  3t/oi/r>«i  V 

-••3;  ••;  ^u; 

Vv'-'V  . . •;. 

•-  r.l  > 

**  S 

, ^'.:.r<  ' , .■  ^ r. 

■ ■-'■^ . d 

’ij.H,-- 'tio't , ao  . i. 

. , 

■ t • 

: / . V - . .-’  C r,  >*i  :;.1  J ,,  •■: : r*  ' .. 

- 'T  c-n.it'r  -'tr  : i.  .*  noi'l  - sX^ri.  :g  *- 

" ■ ■ '-0  - ■■;  J-  ::  -jj;'iV  „ U ;-  ,'  •CfiWtil 


; iiLiifl  . iXiidflC 

. I'fxn  310- ',>*,0  a i an»I.  - 

- .» • j ^ ai  r 5 ^rf—  ; fj  o>i 

-:’  pic.'tiXli  '15  ‘ic^  noLqct/- 

;5  P X w ! 0 1:  r •■•  **  r / j r i j ; nXI> i - 


''■■  • ' * . ' ‘ r i-x  p^-iev-  'io’:  x-X  'o<i:  " 

X t.‘  io  oJ  lo . 

< •')i> J’iiXjjnZ-t ':<  ii!.'  ;i  9>  quXxJG^'i  fil  6:;Xi.'; 

-C  i.V':-  ’ir-  'io  X><  X ' ■ 'v-X  J V aexlw.  , 


o/s*/  ■ 


:<v  'r-^ooX  Jbawii.iia  : Cft^a© 'i'.r o;ij  jx". 

■ * • Xis^pce  .ftX  ftw^  iuei  i-jliailo  <b5T:^'rj®«  ‘'e-j-i' 


•f.  •ri 


■K 


, D 


{ 


r 


« 


s,.*. 


, 'jT-  0 iC  Ic  :{(,v5'i  JX'u’^ 

;.c.'.  aiOt'liX'XI  'io  ...iUxfri.;:'" 

,..orJXXI 

'■■  ■-' ''Cfc'  - ! 

."■(/C.  , , 4 n-  t »:':i 


J 


46 


indicating  that  the  curve  expresses  the  general  law  closely,  but 

the  values  of  the  constant  c4re  not  correct  for  the  ligiit  minerals 

like  coal.  The  figures  commonly  given  for  the  specific  gravity^  of 

coal  and  its  impurities  are  as  follows; 

Presh  Bituminous  Coal  1.  20  « 1. 30 

Shale  2. 6 

Gypsum  2.3 

Pyrite  4.7  -5.1 

Settling  Ratios.  While  these  mathematically  derived 
laws  do  not  completely  explain  all  the  phenomena  -vdiich  take  place 
in  the  washing  operation  they  are  sufficient  to  show  the  underlying 
principle  of  the  hydro-separation  of  minerals.  They  explain  why 
particles  of  different  specific  gravities  may  be  separated  from 
each  other  providing  the  range  of  sizes  is  not  so  great  that  the 
smallest  particles  of  high  specific  gravity  and  tlie  larger  parti- 
cles of  low  specific  gravity  fall  together.  The  ratio  of  sizes  of 
particles,  which  according  to  Rittinger's  law,  will  fall  together, 
may  be  calculated  by  substituting  the  specific  gravities  of  the 
tv;o  raa.terials  in  the  formula,  equating  and  solving  for  D diameter 
0 f particles. 

Vx  s=  K\jj>  (Si-l)  V2  = K\jr>  (S2-I) 

kVDi(  Si-1)  = k\Ij>z{  S2-1) 

Di(Si-l)  = D8(S2-1) 


(3)  = S2-1 

D2  Si-1 

This  equa.tion  gives  the  ratio  of  sizes  of  particles  of 
specific  gravities  Si  and  S2  which  will  settle  at  the  same  rate  in 


^Specific  Gravity  Studies  of  Illinois  Coals,  Merle  L. 
Nebel,  Eng.  Exp.  Sta.  Bull.  89. 


47 

still  water.  This  is  called  their  free  settling  ratio.  Consider- 
ing coal  of  1.25  specific  gravity  and  shale  2.70  specific  gravity 

this  ratio  is  2. 70  - 1 _ 6.8 
1.25  - 1 “ 

The  ratio  of  sizes  of  equal  settling  particles  of  coal 

and  shale  secured  experimentally  by  Rossback  check  the  formula 

closely.  These  experiments  were  on  coal  of  1.21  specific  gravity 

and  shale  of  2.58  specific  gravity.  The  settling  ratio  determined 

by  experiment  and  the  ratio  by  calculation  are  as  follows; 

Experimental  average  for  particles  above  .03'*  diameter  7.0 
Calculated  ratio  7. 5 

This  indicates  that,  theoretically,  with  a raw  coal  in 
which  the  largest  piece  of  clean  coal  is  not  more  than  seven  times 
as  large  as  the  smallest  particle  of  shale  a cleaji  separation  can 
be  effected,  but  if  this  ratio  is  exceeded  the  fine  shale  will  re- 
main with  the  clean  coal. 

The  Natural  Middling  Product  in  Raw  Coal.  The  parti- 
cles in  raw  coal  which  are  to  be  separated  are  clean  coal  on  the 
one  hand  and  shale,  pyrite,  calcite  and  gypsum  on  the  other.  The 
fact  that  these  four  impurities  are  all  much  heavier  than  the  clean 
coal  makes  the  removal  of  particles  of  pure  refuse  comparatively 
simple  unless  they  are  very  small,  but  the  separation  is  always 
rendered  more  or  less  incomplete,  because  of  the  presence  of  mixed 
particles,  part  coal  and  part  refuse,  which  are  not  broken  apart  in 
crushing.  Such  particles,  of  course,  are  intermediate  in  density 
between  clean  coal  and  clean  dirt.  A third  class  of  raw  coal  par- 
ticles which  give  great  trouble  in  washing  consists  of  broken  frag- 
ments of  bands  of  bone  coal  or  light  carbonaceous  shale.  These 
particles  also  are  intermediate  in  density  between  clean  coal  and 


> r'  4 

. 

■^3.'  : ..0  - .;:  I 


t 

I 

1 


■ ‘ M • - . - ■■  Ij  -O'j  f 


- ■ ^ 


1 


'i. 


' ■ <\ 


/ 


f 


3>,  ' - ■ ^ 

I J"  ■•• ..  '■  :,.t 


i 


i 

! 


f 

■i 


ft  jO^  r-  . . . 


► 


■j 


t 


fii.  S':  ■/».:  r:* 


i j 


e 


. .u:)  •v.  -i 


■ « <■  > v/  (.  C I. 


O ^ 


'Tlf 


t 


0 :.  ■ W.  ['z  ■'  . Q 


. ./.T 


. ' ..;:  • : L J :;■  /r  ’ 

' C - : . -S/  5*X  - li  ’ ^ ...  "I  i • J,  . O \) 


' C-. 


I ^ 


J 


48 


clean  refuse.  The  mixed  particles  and  the  hone  coal  and  carbona- 
ceous shale  particles  form  the  hulk  of  the  middling  or  secondary 
product  at  the  washeries.  This  product  is  either  crushed  to  finer 
size  and  rewashed  or  used  around  the  plant  for  fuel.  If  there  is  a 
considerable  proportion  of  this  kind  of  material  in  a raw  coal  it 
is  very  troublesome  for  two  reasons.  In  the  first  place,  such  par- 
ticles are  very  difficult  to  separate  from  the  clean  coal  and  in 
the  second  place,  if  they  are  removed,  it  results  in  a large  reduc- 
tion in  the  amount  of  coal  produced  for  a comparatively  small  im- 
provement in  ash  and  sulfur  content.  This  constitutes  what  is 
probably  the  greatest  difficulty  which  is  met  with  in  washing  coal. 
It  is  particularly  serious  in  many  central  district  coals  which  con- 
tain, when  crushed  to  the  size  at  which  coal  is  commonly  washed,  a 
relatively  large  proportion  of  such  material.  It  would  seem  that 
the  mixed  particles  might  be  eliminated  by  crushing  fine  enou^  to 
break  the  coal  and  the  shale  apart,  but  the  practical  value  of  this 
expedient  is  problematical.  The  effect  of  finer  crushing  in  the 
operation  of  washing  depends  upon  two  opposing  tendencies.  First, 
the  more  finely  a raw  coal  is  crushed,  the  more  completely  will  the 
particles  of  impurity  be  detached  from  the  particles  of  clean  coal. 
Second,  the  finer  a coal  is  crushed,  the  more  difficult  it  becomes 
to  separate  all  of  the  detached  particles  of  clean  refuse  from  the 
particles  of  clean  coal. 

The  bone  and  carbonaceous  shale  cannot  be  cleaned,  as  the 
fine  ash  is  inextricably  mixed  with  the  coal  and  cannot  be  separated 
even  by  fine  crushing.  It  is,  however,  possible  to  remove  such  par- 
ticles entirely  and  discard  the  coal  as  well  as  the  ash.  Specific 
gravity  analyses  of  two  coals  are  shown  graphically  in  Fig.  3. 


■'  r'a  bf.n:x!c  Oil?  r.’isU 

*0  T i: xi  ,■  i' iir  T.1.J  'ic  w/'J’  rr:-.  ; . i)i  _ > j>£iL  : 


■> 


i 


V/Zi-.  > .10' 

* *•  ' •'  “ ’ '1--  -i  Oil!)  O'tr-i  'V  z'  . .* . Jvuiiozz- 

T ’ " * * * A*;!  q or^*  Jini-'OTiJi  {^0it  J Tfo  ■ ),,.  j.vyr 

w -itcO  . -'I  r!  ni  Xi.  i •>-!'* /L~  »■-  i r j * ’i u*i ■:;j  pf  . ,*£  ^ 

« ' =*X t l •)  „ :;I  . jitOiC.'.’iVi:  o-’’v  ' ot; i.^ ; \jfu o*i»l  V'lav 

-V-  ••  ■• -n  «■  . t.;  fmlol. 

, VnZ  ’ 01. coot; 

- * 

J , ■'■  .n  ^ r-rkf-  J 


t .. 


f*  r ^ I*  ^ , * I 


..J. 


^ 1 


‘ -iC-  5 


J:.-V 

L i X , 

• Ui 

P . -lo'i 

^ PO 

AvC 

nl.r'^ 

> - 

* j 

t . 

A , Jt  in 

ii‘> 

:..  b 

Xx'rX.:i? 

-.••  xn. 

'«  T)  ' ,‘ r 


^-r.  ^ 


•ii  J-riO£Pii;V0f '4 


\f.::'  iffoie  ^ 


r \£:x 


>■- 


- ::i  5>ia 


• - J-.-^  .o'  ii  oi’J.  v'  : •■  *3.. 'tv  .lO 

.C'**:  •.V.v  l'vj5}  .,  ■ '■  ; c‘;  or’i  .£  I'l  | 

'^c i . ii . r .."r o v - DP*.-. .!  j .'3i '’ '•  p'  :;‘  Xoiv'i  ■..<  o;.* 

:a-u  it  9J.'I.  ••  I ; r:  :b^  . 'x..^  J-  •‘■r;p'Xr,wO  :>.  .^  >L'>s»'x  j 

o-b  nx  -,;;x '-O.;/ : >c  wOr,  i.o  o:  - * 1 - 0 IJ  , uei  a o-i v.l 

■••■•..  -I 

t'-  , xono-..:  c v::..oo.i(^o  xiot'"  iiirKOqj'O  vr  1-  6 q 

."i:  / v/o^  0 :■;.  LuV’  p-x^-  • ;j  ,*  ';j.-'-:o  fix  I ;oo  V.UH  /j  \Z^ni\  ^to:n 

• ' i 

x-:c:-  .;  Dio  lo  ooXoi.l'i  ov.'v"  .;00'i  ■ bo  "'or’w g .'  v" trD^’oi  J”i-''’P  fi| 

^ 1 

.'!  - G.o.:  :•  : ft'tosn  Pt.  , '»i-fG'-tD  :-;i  Xhod  Jt;  'lOitxl  5 ;J-  ,*>r.ooo.:r 

i ....  •'  ■ 

.0...  a:o'^  :in:;co'i  :\  vIg  '.p  oo‘oib'1.  ,.  b :>b  pd:?  “io  xi^  n3  ^■zz»q(^  o3  I 

. '’  >0  y To 


O.-J  :..  . 

.:..’‘j.^y 

dX 

b Oil.MiP,.  eijv  i„.  : -00 

n-j  .;'i.  ■ , 

oo'  .?OXT 

-Til  /.-■CO 

Grr.f 

•f  -»  ;::''y'. ; 

olZi  :yc)iu 

G'’'«>vy/ 

oi.Txooq: 

*• 

r.u  £i'g.’ 

•'■  • I -oa  p. 

« 

• t * A. 

ir  r ; 

..  Gii-I.j  ,'rr, 

/'^.vorfc  o'r.')-. 

i 

»■■  i - 

■ . - . 

- 

2f ''xa.;:..  -,1  r XI 

.1 


50 


These  show  the  percentages  o f material  of  different  densities  in  raw 
coal  crushed  and  prepared  for  washing.  The  lengths  of  the  horizon- 
tal lines  show  the  relative  proportions  of  the  increments  of  the 
specific  gravities  indicated.  Those  included  in  the  bracket  make 
up  the  natural  middling  product  which  gives  difficulty  in  washing. 

It  will  be  noted  that  the  coal  designated  as  non-washable  contains 
a much  larger  percentage  of  this  material  than  tlie  washable  coal. 
This  difference  in  percentage  of  natural  middling  explains  in  a 
large  measure  their  difference  in  washability,  . 

These  graphs  show  plainly  that  raw  coal  consists  of  a mix- 
ture of  particles  of  all  specific  gravities  between  that  of  clean 
coal  and  that  of  clean  refuse  and  that  no  definite  natural  line  of 
division  exists  between  the  coal  and  the  refuse  on  the  basis  of  spe- 
cific gravity.  The  zone  of  separation  in  actual  coal  washing  prac- 
tice corresponds  approximately  to  the  middling  zone  marked  out  by 
the  brackets, or  perhaps  a little  narrower,  say  from  1.35  to  1.60  in 
specific  gravity,  but  shifting  up  and  down  somewhat,  depending  upon 
the  grade  of  washed  coal  being  produced.  The  ash  and  sulfur  per- 
centages in  the  various  fractions  of  different  densities  in  these 
coals  are  shown  in  Table  3. 


t 't;.  ?;r-o;u ‘I  :.,.i  r,:{J  , : . .J.J 


■-t.' 


■M'^n.rriifc  :••  .’rt  l'fv  r.  x.  'lu^eri  -^^W' rfj* 

\ '^- — ■ A'l 


rini'v.T  ••  0, 


• V 


I 


' J. X"  C 

: X'  ci/ij  ’ 

'■'■'■  .•■.;.■■  i y,I.  L?!;!  " 


‘.‘  -J  Xr  J 


• A-  ',  • , . ,r  v 


* i ^ ^ 


I 


’ c 


pi*“?  \ ;X  iri  ii  ■’ il :;  T j ;>n';  iAi 


J - 't'}  ’^"‘... 

f XX 

i . ''. 

, l^ui  1* 

,■/. ...  'iC^U:,-  . 

■ ■"  V ■ ri  e>c.  , 

■t':  :1it5 

/.'AiC-ai 

T 'X 

k.a  ’ 

*‘i 

I*  ii  ’ •*■■  ■-  K ' 

'►V  • . -4,  V 

'X.iq  1rc( 

c;x4w' 

'-J  J; 

.'  vX  h -'i_’> 

i»ft/''  . .<?BX 

:%o  ..ci 

iXV 

iikUfittixw  r r.n  J.L.jSor.  f»i  r«  -i  IJ«  If  !‘.-os  o/‘’’  ♦ oXlln 


fff 


C"f-‘  0.*  • ;"  J.‘  ..t  : A'y  7 


ax 


V , >•'  'i*:  ■:»*’•*  <5c,/  .4'r'v.i  « »= 


i , : •’  r n 

” '"i : r::  ‘i ..  . f»'» ^ :■ 


i 


. ■ •< 

i.5 


•rroTT  ;p'  .l!*a  i :oo  ^ j :>  t\X  ,*r 


J a 


■•  X fM.  . :.  ,:M ax'  fi;,  '.,v  f!.'r  nl 


h 

i 

,i  c/ 


* 


n 


a 


t (TA-Or*..'  I:IjS3  5 


51 


TABLE  3 

Specific  Gravity  Analyses  of  a Washable 
and  of  a Non-washable  Coal 


Washable  Coal  Non-washable  Coal 

Specific 


Gravity 

Per  Cent 

Ash 

Sulfur 

Per  Cent 

Ash 

Sulfur 

of  Total 

Per 

Per 

of  Total 

Per 

Per 

Sample 

Cent 

Cent 

Sample 

Cent 

Cent 

1.30 

73.35 

4.64 

1.72 

55.9 

10.1 

2.91 

1.30 

to 

1.35 

8.74 

11.27 

2.14 

20.  5 

13.3 

3.35 

1.35 

to 

1.40 

4.93 

17.78 

2,  39 

11.8 

15.4 

3.  45 

1.40 

to 

1.45 

1.82 

20.32 

2.  52 

3.8 

19. 1 

4.39 

1.45 

to 

1.  50 

0.39 

24.60 

2.  62 

1.8 

22.  5 

6.18 

1.50 

to 

1.60 

1. 12 

29.90 

2.80 

2.1 

27.6 

9.29 

1.60 

to 

1.80 

2. 13 

49.  53 

3.43 

1. 1 

42.7 

13.30 

1.  80— 

7.52 

84.04 

13.63 

3.0 

60.  5 

34. 12 

10. 

Relation  of 

Specific 

Gravity  and  Ash  Content 

PJl  Co^l. 

This  table  giving  the  ash  content  of  fractions  of  the  same  specific 


gravity  in  different  products  from  the  same  coal  she  that  a defi- 
nite relation  exists  between  the  specific  gravity  of  raw  coal  par- 
ticles and  their  ash  content.  It  will  be  noted  that  in  a given 
coal  fractions  of  the  same  specific  gravity  have  practically  the 
same  ash  content.  The  coal  samples  were  divided  into  these  various 
pa.rts  by  immersing  in  a zinc  chloride  solution  of  1.25  specific 
gravity  and  pouring  off  the  float  then  immersing  the  sink  in  a ser- 
ies of  heavier  solutions  varying  in  specific  gravity  up  to  1.80 
and  analyzing  each  float  product  separately. 

In  1893  E.  B,  Coxe, in  an  address  before  the  New  England 
Cotton  Manufacturers*  Association,  stated  that  there  is  without 
doubt  a close  relation  between  the  specific  gravity  of  coal  and  its 
percentage  of  ash.  A great  number  of  specific  gravity  determina- 
tions and  analyses  made  at  his  laboratory  at  Drlfton,  Pennsylvania, 


52 

led  to  the  conclusion  that  for  a given  size  of  coal  from  a given 
mine,  a specific  gravity  determination  on  an  average  sample  will 
give  very  nearly  as  accurate  an  indication  of  the  ash  content  as 
will  incineration,  althou^  the  relation  between  ash  and  specific 
gravity  may  not  be  the  same  for  different  coals  or  different  sizes 
of  coal.  Nebel^  gives  the  figures  for  ash  content  and  specific 
gravity  of  a number  of  bri^t  coal  and  dull  coal  samples  from  Illi- 
nois mines  showing  that  the  dull  coal  in  every  case  was  higher  in 
ash  content  and  hi^er  in  specific  gravity  than  the  bri^t  coal. 

The  curves  in  Fig.  4 show  the  relation  between  ash  and 
sulfur  content  and  specific  gravity  for  a number  of  coals  which 
were  examined  as  to  washability.  The  ash  specific  gravity  curves 
are  all  practically  strai^t  lines  showing  a fairly  uniform  increase 
in  ash  content  with  increased  density.  Since  the  calorific  value 
varies  quite  uniformly  with  the  ash  content,  the  relation  between 
B.  t.  u.  and  specific  gravity  will  also  be  fairly  constant. 

11.  Relation  Between  Specific  Gravity  and  Sulfur  Content. 
The  percentage  of  sulfur  in  fractions  of  a given  range  in  specific 
gravity  in  a coal  shows  considerably  more  variation  than  the  ash, 
yet  the  approximate  checks  were  secured  in  the  coals  examined  and 
the  curve,  Fig.  4,  shows  a comparatively  uniform  increase  in  sulfur 
content  with  increasing  specific  gravity.  This  will  usually  be 
true  of  high  sulfur  coals  containing  much  pyrite.  Low  sulfur,  hi^ 
ash  coals  on  the  other  hand,  may  be  very  erratic  in  this  respect 
because  the  increased  wei^it  of  the  heavy  particles  may  be  all  due 
to  ash.  Cases  have  been  observed  where  the  heavier  raaterial  con- 

^Specific  Gravity  Studies  of  Illinois  Coals,  Eng.  Exp. 

Sta.  Bull.  69. 


, TCf.t  t 


’■rfj 


lA  ^ ^ V ' 

jv-.r;  ,.i 

- ~ * ! 

J i:4>  f;  . ,; 

* '.'  i.r  * ' 

- • ‘ - ' : i.  -jfJ.;  ; 

• 1 

Xi'XM^:  v*£9t 

t'.r  ' • .. 

.'  ' ■<v-‘^  *>  .' 

,TOi^.«rA  •■' 

:o  V 

; -cc  ^ ir 

‘i-'lli  -ic'c  :i;.->u, 

r .. 

• V-  . i - , i.  ^ • 

\ 

■ ;ur  -ii  • 

•■  ••  ■ .*  ?ftri  ' 

j;-> 

•VO  ■ il(..'  ■ 

XdOo  .*  , I't  iC  I-  . 

^ LOT’.  ic  ’i--’  •: 

r • 

-''rik/i  ■ lii  r 

'*  .t  ' J-. ...  **  .-J  .-r 

•v‘  .,:xv 

-X-  '..;■*  ' . ,;  ;•: 

wpc:. 

' -.Jrrbo 

* ?;*'  iioir  :. 


. J . , 


: 


>;  J.  1 


•r  ^■ 


ip; 


p:£T 


■‘tioaqn  Z;  iiji 


V ■':.&  aM- 

;v 

- *'r^-ob  .-a:;*!  i^psm  '■  ir. 

* '^  i .'  ■ - ■;.  ‘ 

or.i;..  . --'1^  oi'ii.r.  '.-... 

.••  .r:  ' 

•'  ' ^'•-  o-  'X*  1 ..  *4'.  ■:  ;',  ; o I * • 

■ ‘ i'l.’  ■•'■'■:'  ■ ' L'.  «i,.' : ‘ v.  , ai  ly 

■'  ' 

rUo^rlQ  .,.'  I ' -:qq& 

® . • .^VT'/C 

*1  ’ - • * ‘ * .*  - * ■*  w 1/  . 


nr.--'  nci:,?,  :. -i-;'  ^ 


aoi-r..  r 


:>  '.  .h  '1 1 


•r  ... . 


f3,:  J ■ 


] .• 


V'i*:*/  ■■  — i-v 


- 1 .•  J '•; 

'■'I 


rf  » «• 


♦ »,^- 


;■  ’i.P, 


J’l 


; / 


-k  ■■  )TD  :,i 


54 


tained  less  sulfur  than  the  raw  coal  and  the  washed  coal  contained 
more,  because  the  sulfur  being  mostly  in  the  organic  form  and  com- 
bined with  the  coal  was  slightly  concentrated  by  the  removal  of 
heavy  shale  and  slate  which  contained  no  sulfur.  Such  occurrences, 
however,  are  exceptional. 

12.  Distinction  Between  Coal  and  Refuse.  Theoretically 
a perfect  coal  washing  process  should  enable  the  operator  to  make 
the  separation  between  the  clean  coal  and  the  refuse  product  at  any 
desired  specific  gravity  and,  as  the  graphs  of  Fig.  3. show  the  raw 
coal  to  contain  material  of  every  degree  of  specific  gravity  rang- 
ing from  a little  less  than  1.25  to  over  1.80  and  of  every  degree 
of  impurity  between  the  minimum  in  the  lightest  product  and  the 
maximum  in  the  heaviest  product,  accurate  definitions  of  the  terms 
“coal^  and  "refuse"  are  essential. 

To  formulate  an  abstract  scientific  definition  of  coal  as 
distinct  from  refuse  would  be  a difficult  task,  and  would  probably 
be  of  little  value  in  the  actual  adjustment  of  a washer.  It  might 
be  defined  as  the  moisture,  ash,  and  sulfur  free  combustible  matter 
of  the  coal  or  limited  to  the  material  derived  from  the  original 
vegetable  material  laid  down  to  form  the  bed,  excluding  interbedded 
or  subsequently  deposited  mineral  matter,  but  neither  of  these  defi- 
nitions would  be  practicable  for  determining  the  standard  of  purity 
for  the  washed  coal. 

The  distinction  between  coal  and  refuse  as  it  applies  to 
practical  washery  operation  is  purely  a problem  in  economics  which 
must  be  worked  out  separately  for  each  individual  operation  or  each 
new  set  of  conditions  as  they  are  met.  One  of  the  most  important 
considerations  is  the  use  to  which  the  washed  coal  is  to  be  put. 


CO 


TOv 


^ i 


fii  ; ifd^  VXi^J  •: 


r.l  N'C^oo:.;. : f n:;:io 

• 

- 'i.;* jooo  ‘..j  / ^ .1  :. (3  .,  - 

cjt:  ; :'j 

• • ♦ 

,.w  - *•.., 

■ •'■  .i  ' ■■'•  oJcl€  ftl.'i'fii 't£vco.'. 

¥ 

-• 

' ' 

'.  :r..  ■ •:  7 r u; 

:’oA'  ..  . ' ■'1'Xtrt-  •■> 

'-.-.'•j  ■/  ••  0 afii- 

■ * ' ■ r.olJ  . 

f < 

• ’ '.  ‘"'w'  ^ ••'  . ■ 'i.v  J y’’  -. 

t;  bti^Xr^:': 

•■7,  ..  • -.►.■■ 

C-  -j  . ,:oo  04  Tcwi: 

0 '-  ■ 0 ; • . ; 

X . ’It  V C oi  ^ f,  0 

* >-  ;V  - ,I  :i  I..:)!  i 

- •'  *;i  Ta/a^ai 

*.  V *;4 i-tEwiicii.  to 

. . ■ ,,f  ft'r:  ; -1 

i.l  ttirniuV^  ' 

t 3 . . 

" •ih'z'ix**  ■■  *'S.  ,K.  '• 

r ' 1.  ' -■■  ■ u 

. • , '^  i i'Q  /C  j j 

‘ ■•rc-J  oT- 

Jb:i  , '•  . 

* V (.  V ^ X ' 7 ' ' - j t,!Q'  ■ •, 

‘-C\ 

J'-:  •:  .♦■•:-  4f  ' ;■.  . .:  oi 

f2oI  ' ■/  Z.  i,  : r 

- J rt  u ,>^^i  .«ab 

'■'  : :Trz  i :■  :)• 

lM"r'7,r.r  0 ♦ -j 

^ j 

ts^u'  -T.  Ici.oo 

- ' yVv^-*  ■, 

■ l-tulox  , 

-OiJ  rrto)’  • j 

a.  nil.'vJ.’iJJ  ; 

'i  "*■ ' i '■»  ■ 

, .^/  •':  : ::cJ 

' .7.  -0 

• ’ »;  ’■  :iO(f  .i  • I J • - *.•  01 

• - ^ i -»•'.*  '5.  • ^■‘  ;o  \yxf^  ' ' 'i, 

“is 

■ -i**  ' • ■ ■''. ■ .t . .■-.  i 1,(00  J 0^  S 


55 


On  this  basis  coal  washeries  may  be  separated  broadly  into  two 
groups  in  which  the  conditions  are  altogether  different^  first, 
washeries  for  coking  coal, and  second,  washeries  for  fuel  coal.  A 
washed  coal  which  is  to  be  made  into  coke  for  metallurgical  use 
must  meet  certain  hard  and  fast  requirements  in  regard  to  ash  and 
sulfur  content  and  if  it  can  be  made  to  meet  these  requirements  it 
will  have  a much  greater  unit  value  than  if  it  has  to  be  used  for 
fuel.  For  these  reasons,  as  a rule,  a larger  proportion  of  the  raw 
coal  must  be,  and  can  profitably  be,  discarded  as  refuse  in  washing 
coal  for  coking  than  in  washing  coal  for  fuel.  For  instance  in 
washing  either  of  the  coals  represented  by  the  graphs  of  Fig.  3. 

If  the  washed  coal  is  to  be  used  for  coking,  an  attempt  will  be 
made,  in  order  to  produce  a good  coke  from  these  high  sulfur  coals, 
to  make  the  separation  between  coal  and  refuse  at  as  low  a specific 
gravity  as  possible,  say  between  1.30  and  1.45,  althou^  some  of 
the  material  discarded  as  refuse  will,  as  shown  in  Table  3,  contain 
only  about  17  per  cent  ash.  On  the  other  hand  if  the  washed  coal 
is  to  be  marketed  as  fuel  the  principal  object  of  washing  is  to  im- 
prove the  appearance  by  removing  the  more  conspicuous  particles  of 
pure  shale  and  pyrite  and  the  separation  should  be  made  at  a much 
higher  specific  gravity,  removing  probably  only  the  material  heavier 
tlian  1.80.  The  increased  market  value  added  to  a fuel  coal  by  wash- 
ing is  not  sufficient  to  enable  the  operator,  without  financial 
loss,  to  throw  away  as  washery  refuse  any  large  percentage  of  his 
raw  coal.  This  is  the  condition  which  normally  exists  at  Illinois 
washeries  preparing  coal  for  the  market.  The  economic  limit  on 
their  refuse  would  be  zero  v/ere  it  not  for  the  fact  that  at  times 
washing  makes  possible  the  sale  of  more  coal  or  the  sale  of  sizes 


If 


'^1 


o,*.,;  V..0  cT-:'  •''d  , (?)  •;  v_dfi  ■ ■’*j, .j-;  ,Xvv’.00  tfl  f -.iz'd’  -hO 

jj  ■‘•  - a:,  - ad?  a ■ -*.  bKj  rfoi  ' ; .— ■ 

'O'  0 /1  *fw  r ? . • ..:•  • ,I«oo  : . .a ..  . 

^ ' 1 ? v.u'.  a-D  v/'.’i  • a*  '. / ’'jiriw  liico 

‘J*  ?/  .'  ■ ;V  art*  3-ilt/j.O'i  d.3-;.  d3*n»’  fCi" 

•'  . ''  ■ 3d  - 0^ 


‘i  r... 


C- Vi'-  'Ijt  .?  odi'.oo 

V u " 

■a  * -x  .5 


' a '*•  t \ » 1 i-  ^ , «% 


a , - *-;'  10H  . >.1/'^ 

A 

•'  ■'  ■ •'  ' « •/'■■■*  X.'<  ’ dTl  -i  ; .1  -.•  1'  , v.^•iL^?.  t'ic.-) 

-'  X'.i  .1.,..  V .ti  ■ :f  y_;ii.^oo 

«*v_ 

8n  'j  ■jr'j  vcf  O''/  *•  -T^xt'ax  .:4.  >''  ■ “ 


i V ^ V ' 5 •*  ' * J[ 


' 1 ' i T ? 


• ••  *ji  , 

t 

■I'  vj»(fJ  ; . 

H M <J  ,i  fiA’t  ’' 


X-  .o-j  *)c^riw  -i’.  - 
* bJ  '....: 


a.a- 


i'''  ■ . ■)'  .,r,flr  : 

‘ -*  .'Ira'  v.X  ..  .oxT 

••  \ f J.  X"  .lOi/'i  !>  ■}  -';,£■  V -V..-  .. 


1C  I.  .“>  ■»  •;  oJ  • i t.  t 1 

•'*'  ■■■  •..!  X-'oX  .1  , aj- 

k ; d ;'i  -■  ? ? / a:D*,tT  c.t 

vfi).v.rrv,j  ^ nii.  ',,dAr«'r' 

•'  ■'  t,.r  '*'r  •j'jlii  .Tft4'I?di<5;B  Or‘' 

■ 1‘7  '■  . 

^ *4 

i. .-:  /.I. a ?:jk  .if.'/-  •.  o f od  :i: 

'/vufiiBX  Vvi  >.j‘  ■’I  ■*.  •C'j  0 !d  '".'Oil 

. Oiid  n&i-.-'r'  «>';j:i'a'  fiX'iJC 

, ’ ■ ^ 'X'.  C-i'a  'JBf  'C  r . ■ 

• ’*»**'  ^ i *,  » » -*■»- 


- - : : d.  ;cr^d. 

:0'X3’.T 


"?• 


- ^ c • X 


©.is  ’a  i .u.“j  t/  .j  n.':  j od'ilL:;.,..  d (Ci!  '.1 

\,nr.  ':r>r\  ,-r  \y' ,'V^  y : \y-’Vy  V\'r:-  'd  - , . .. 

nOiJis'j'tOO  . .'5j  v lii.*  . 'iO 

* 

a a*i  V Sy:C:)  .i  iixc.f.'vcv^ 

id  d . d.i.'s’  . r;  t . ov  .:  o ; ra^-'o-v , 0 a.: . T 1 ’ d 

a ^ad  -ci  r.<y\  i a:.j  ©a.^:  .q  ao:  a rt^x^.• 


i:a  J i.  jif,  otiiii  . 0 j n.' 


which  otherwise  could  not  be  disposed  of. 

Within  certain  limits  the  separation  between  coal  and 


refuse  is  under  the  control  of  the  washery  operator,  who  has  two 
principal  motives  in  view;  namely,  to  produce  as  clean  a washed 
coal  as  possible  and  to  recover  as  much  as  possible  of  the  raw  coal 
in  the  washed  product.  These  two  objects  are  conflicting,  and  in  an 
efficiently  operated  washery  considerable  improvement  in  either  one 
can  be  secured  only  by  some  sacrifice  in  the  other.  Table  4 gives 
the  results  secured  in  a washing  test  on  a sample  of  coal  from  the 
Number  3 seam  in  Indiana.  This  coal  was  washed  on  a concentrating 
table  and  separated  into  sixteen  products  varying  in  purity  from 
the  cleanest  coal  to  the  cleanest  refuse. 

This  shows  the  purity  of  washed  coal  secured  and  the  pro- 
portion of  the  raw  coal  Yhich  is  saved  in  making  the  separation  be- 
tween coal  and  refuse  at  any  one  of  the  fifteen  points  where  prod- 
ucts were  separated  in  this  test. 


'-^  ' ''■'-I'"'-'  ;..‘'Ji«:vj 

t w 'r-'rc  vr  ■■t.M'  lo-^r-oo  otlf  at  -ei/io 


4::,  oouC>b‘r’ 

- ^'Ticrt  tJ  ’.i.. 


: > rt  ■'  ■ 


;T-'iv  li  r ^'vi^Qu.  *. 


o,t^  1SVC-i.:-i  0^^fv.«  vi  JiSGOfT 


c ' O','  o'Z  ovri  :"'r,.:V  . : o’la  l)?7.-'s  r»rl?f 

■•■  :,*'•'  -.1^  ir\  • c';;  .’j  ':I  ’ >•:  • i.  \.n:arl‘:'V'  'o**  r.Ta.-r-  -^1 ' cdlftillr* 

■^■*  > .•  I>  >»  -.  • . ••  '*-  • ,,  -,..  ..  ■ . i-.... 

■ Vw  * ,-•'.■  j #•  i*; 0(3>r: 

* L • ^ 1.  i-  - * ■ ' »%  f . V ^ ? ..  - 1 ^ ' . _ 

* ‘ • .-•  ,,i  J •'.  j'l'.M.T  IJ 


' - ' ’ •■*“■  X>^cr)  -3^;:’."  , . * ' ’i*?  ’iifu; 

ri"-5*xi.-ii  Ciiiii;  ?i  bcii  ril  i J 

• ■.  1 J A ;>  9X1^  0«  .(  'r-o  itiiJ.,  3i.O  «»  iJ 

- '•  •o-'  .'  -Tr  ■ V-  7*x  ; • r:--:*  a -lii;!* 

'•*  ' ."  •-  ■•  -I  ’ >icuv  ' j ir-'i  i • 4*1  oiJ’  c] 

■'■0/  ■.  ; ni.,-.  pn  „ 

' ' -‘-i  •'■  'i  . -j-  ^’rarr  njox 


I ' . 


I 


Mr- 

•■  I’ 


.ii 


TABLE  4 


57 


Recoveries  and  Ash  Contents  of  Washed  Coal 
Prom  a Sample  of  Indiana  No*  3 Coal 


Product 

Number 

Per  cent 
of  Feed 

Per  cent 
Ash 

Cumulative  Per 
cent  of  Feed 

Cumulative  Per 
cent  Ash 

1 

4. 8 

5.03 

4.8 

5.  03 

2 

5.2 

5. 14 

10.0 

5.09 

3 

4.1 

5.32 

14. 1 

5. 15 

4 

2.9 

5.64 

17.0 

5.  23 

5 

5.  5 

5.77 

22.  5 

5.  36 

6 

5.2 

6. 13 

27.7 

5.  50 

7 

6.1 

6,45 

33.8 

5,70 

8 

4.8 

6.97 

38.6 

5.84 

9 

6.  6 

6.60 

45.2 

5.95 

10 

7.8 

8.20 

53.0 

6.30 

11 

11.6 

10.20 

64.6 

7,00 

12 

12.2 

10.85 

76.8 

7.  50 

13 

8.9 

18.  57 

85.7 

8.70 

14 

7.8 

45.05 

93.  5 

11,70 

15 

4.6 

78.00 

98, 1 

14.  80 

16 

2.0 

58.92 

100.0 

15.70 

In  Pig.  5 per  cent  recovery  is  plotted  against  per  cent 
ash  in  the  washed  coal.  These  figures  show  the  possible  range  of 
adjustment  of  the  zone  of  separation  for  this  coal,  giving  on  the 
one  extreme  a maximum  recovery  of  100  per  cent  with  no  washing  and 
on  the  other  extreme  a recovery  of  10  per  cent  of  the  rav/  coal  in  a 
washed  coal  product  of  5.10  per  cent  ash. 

In  any  case  the  separation  desired  is  the  one  that  will 
give  tlie  largest  possible  recovery  of  clean  coal  which  will  be  suf- 
ficiently pure  to  satisfy  the  requirements.  This  is  the  condition 
which  will  result  in  the  greatest  return  from  a given  tonnage  of 
raw  coal  treated. 


,N 


t 


4^ 


is 


r 


‘ V -’Z 


■'**-. i f.'- 


4. 


M 


1 


j 


percent  yie/c/ 


/o 

20 

20 

40 

\ySO 

\ 

,60 

i 

I 

70 

\80~ 

Po 

/oo 


/ Z 3 


.Percd\ftt  Peh 


5>  M //  }2  /3  U /6  /6 


/ Z 3 4 2 e 2 8 ^ h N /Z  t3  h4  ^6  6<6 


: Percent  A^h  \ | : 

Fig, 5 — yield  Peh  C^rve^  fable  V^a^blng  ^b'st 

on  0 — Coal.,  _i 


f 


59 


CHAPTER  IV 

DEVELOPIJOUNT  OP  THE  PRACTICE  OF  WASHING  COAL 

13.  First  Metho ds  of  Cleaning;  Coal  V/i th  Water.  The  ear- 
liest reports  of  the  use  of  wet  methods  for  cleaning  coal  show  that 
from  the  beginning  the  processes  and  machines  used  for  improving 
the  quality  of  coal  have  been  developed  in  connection  with  the  met- 
allurgical industries  and  have  been  brought  a,bout  by  the  demands 
for  better  coke. 

Crude  methods  of  v/ashing  coal,  by  drenching  it  with  water, 
were  in  use  in  Germany,  France  and  Belgium  in  the  first  part  of  the 
Nineteenth  Century.  The  first  results  recorded  concern  the  experi- 
ments of  M.  Marsilly^  with  coals  from  the  Valenciennes  district. 

The  apparatus  used  was  called  a gailleterie,  and  consisted  of  strong 
sieves*  upon  which  a stream  of  v;ater  fell.  '’The  largest  pieces, 
called  gailletes,  about  two  inches  in  size  were  retained  in  the 
first  sieve.  The  gailletins,  or  second  size,  were  composed  of 
pieces  of  about  one-third  of  a cubic  inch  and  in  the  third,  or  tails 
sieve,  a.ll  the  friable  earthy  and  pyritious  impurities  accumulated." 
The  first  product  7/as  further  cleaned  by  hand  picking  to  remove 
coarse  shale.  This  produced  a.  good  coke  carrying  6 to  7 per  cent 
ash*  The  second  product  yielded  a poorer  quality  of  coke  of  7 to  11 
per  cent  ash.  In  a similar  process  used  at  Comiaentry  Colliery  the 
crushed  raw  coal  was  flushed  with  water  down  a sli^tly  inclined 
trou^,  with  gratings  placed  across  at  intervals  to  retain  the 
coarse  pieces  and  permit  the  fine  coal  end  earthy  material  to  be 

%ussprattte  Chemical  Dictionary,  p.  94. 


o T.‘)  .) 


• .y.  ' 1 . . \'j  c'‘ori  ' 


? ^.,  ; :•  * \.r  , *.'  ■ l ^ • '1  , ni  ■>  . ■ ‘t  < 


'it:; 


60 


washed  on  out  of  the  trou^,  A method  of  removing  the  cla,y  or  shale 
dust  from  coal  by  drenching  it  while  on  the  screens  or  on  the  car 
before  shipment,  with  a stream  of  water  was  not  uncommonly  used  in 
the  early  days  of  the  coal  business  in  America,  In  the  anthracite 
field  especially  this  process  was  sometimes  referred  to  as  coal 
washing  and  has  been  confused  with  the  specific  gravity  separation 
now  designated  as  coal  washing. 

These  were  merely  wet  screening  processes  which,  due  to 
the  fact  that  the  refuse  and  the  dirtier  parts  of  the  coal  are  usu- 
ally more  friable  than  the  clean  coal,  makes  a rou^  separation  be- 
tv/e'en  the  best  coal  and  the  dirty  coal.  An  improved  form  of  trou^ 
washer  similar  to  that  used  at  Commentry,  but  with  low  dams  or  rif- 
fles placed  across  the  trou^  at  intervals  to  arrest  the  flow  of 
the  heavy  impurities  and  cause  them  to  collect  where  they  can  be 
shoveled  out,  was  commonly  used  until  comparatively  recently  in  the 
British  coal  fields.  This  was  the  first  kind  of  washer  in  which  a 
separation  was  made  between  coal  and  refuse  by  virtue  of  their  dif- 
ference in  specific  gravity. 

As  far  back  as  1826^  a washer  of  this  kind,  then  called  a 
step  washer,  was  used  in  the  valley  of  the  Tarand  near  Dresden 
Sgjcony  for  cleaning  slack  coal  for  coking.  "A  continuous  stream  of 
v/ater  from  a superior  reservoir  is  directed  upon  a flat  chest,  the 
bottom  of  which  is  formed  of  two  steps  inclined  1.5  inches  per  foot 
against  the  stream.  The  second  step  is  lower  than  the  first  and  is 
succeeded  by  a table  of  wickerwork  or  a perforated  metallic  sheet 
upon  v/hich  the  washed  coal  is  drained.  A low  flat  board  across  the 

^Coal  V/ashing,  Arthur  Beckwith;  Van  No  strands  Mag,  , April, 


1870 


: ■ ■■  * 'Ijr  V 

. r..'  ’>*' v r "fcr.'aHOorir  ‘ 'Jr;'  .< 

r«v2.r:  V . n:  .•jt;:'-' 


> ;JL  (nt  j v.'i 


. .:0  I • ;.■■'■ 

•:  T'US'^; 

V-  . • 

N " 

lid  -c 


n ua  J ^ T j -I  ■ ■ % ^ 


/:  i. '’'M't  i.  :•  31  ' •.•  \ C '.»*■- s 5T« 

■ 


iJ-  top  rteO'Jv<3^4  das 

''•  ...  . i :'h  'r»‘'Oi‘- 


■ .r.  '>4 " •> . v:  . : .ii  .(3o'; 


•• 


. f * n 


■*  ’ ■ •«  i.  3*t  3 } 

;^.D  11.:' 13  a.'^' 


. i'X".  Ttv  . \- 


I:’ 


•?c 


fi  £<)^Q0  I :'ro  • * 

x»  ; • c?3f 


'iw  nil' 


.ir  'b 


':o  ■.  ■: 

n: 
: i ^ 


y > 


, - 1 1 'I  i ' V -1  rui  i i i '.i'  Hi 


oj"  :c..  '•  -V  -rv:_3'  " 

'*  .13m. 

■T  L ..i  'tnrfn,*  ■ ? .c?'  «.’4i : li.  ' 

-.'  • • i-'  ’t  'll-  IP  r*‘-:  / J . I C-..  .:••;•  •,•?- \ r,!.|lG&,,''..vr  u : 

. r.l  fvi ’•''T  ^’r 

1 .ic.,  , 'O  lid  ..y  .;i  ’‘‘  "t.j  \ 

’■■>-.  ■,  ->•;  7 . 't;oX  ...V  O-'v  *J  jOG7  y. 


. ^ 


U r,i  : 'j’l  .’t’  * ..Oi} 

'.■)■:•'  f'-  ; .‘'r(.)i:‘  ••..’■  ,d.  .[-..Cv-ri  n.;.>Ja  C'..’^" 


I 4 30  •.'■pii.C  ; ■:  .,1-  o T«>'  ‘..,--0*:,  '- 


^ 7 i C'  Vi  9 € •:  i '10  /.  'i  .=?  If  Wfl 


t -'\ 


■'r7  aOv  3'.? ',l[;  ;j 

& 

c ,■'*.>  Cf  . ji  j 


S'?  o.vj  -f  .':  A . o ’/  n '■ 


'0.*  n„ 


f .,  • r 


J ,CC.'i/*'r  '-oi  oio'lidti  • ■:  -'lOT-idAuiv 


‘fA-  o.-  / 0. 'i 


.f^  5»no  '■ 


ot  r 


1'  I*:”  11  r 


• r ^ ’*f 


xb  i:i  I^C/V  i-‘0 


» * 


.-tX 


3V.  :'i*bOJi  , 


^ » .f  #•.  *1  »l'  • r/  i # • I f I '. 

J«  ' V*  •**%  A*4  4<4  *»|  ^ •4mU  -^'* 


61 


upper  end  of  each  step  serves  as  a dam  to  arrest  the  slate,  stones 
and  denser  bodies.  V/hen  these  have  accumulated  sufficiently  upon 
the  steps  the  washing  operation  is  stopped  for  a short  time  and 
they  are  shoveled  out.” 


Fig.  6,  Early  Step  Washer  used  in  the  Tarand  Valley. 

14.  Early  Hand  Jigs.  The  first  machine  which  made  use  of 
an  intermittent  rising  current  of  water  to  make  the  separation  be- 
tween coal  and  refuse  was  the  hand  jig,  a machine  which  was  origi- 
nally developed  for  separating  metalliferous  ores  from  their  gangue 
rock.  Agricola^  describes  a crude  form  of  jig  which  was  used  in  the 
Sixteenth  Century.  This  was  a round  sieve  bottomed  basket  v;ith  han- 
dles on  the  sides  which  was  filled  with  ore  and  jerked  up  and  down 
in  a tub  of  v;ater.  After  jigging  for  a sufficient  length  of  time  to 
stratify  the  particles,  the  lighter  waste  rock  was  skimmed  off  the 
top  and  discarded  leaving  a layer  of  heavy  concentrate  in  the  bottom 

^De  Re  Metallica,  1556;  translation  by  Herbert  Hoover. 


, lie ' r*J-  TTrf' 

o'*w  :»o.> 

V »t  . •■•.  ' ’•  • ■ r:-’.c  ? A'i'i'.'io  ?.  >.  '•7'  'c.qsf*. 

■ :>:1  -JVOjfei  M irt  “v 


i 


. » 


T^f  i f'r  ■'  ^ - 1-  •l.t”'  - ■'^•j  J.i  * 

.♦ . - «»..•*•  oV- • ; o.?  •r.^j..  V ■•■  ef.trX'Ii'r'  : .’ i '.. 

■•  I -•  • , jr;.  ©{(#  *r-s''^  • •_ .:  ;/->so;i  frt 

:vri.<  :s;  *xc-  v 


. - ^ . ' i 


'’  X . I 


‘‘  ' 

J.  J 9 


•*  'J 


zi  .i'‘;-n/^‘Oi  -bv^i.1.2  i ■ u. 

■i  ; . >•:  . b'lf'XlT  oii'  . i '.V  .'. 

:o  -''vriri'  /.  i.  Jz,  . ►•:’Vw/5^:r  .’l  ■ 

..  , o -t./.:  u>:’.v  -.tv.  ’•••*  -■I'jJ.'  -IX  9iff'  ',  J'f '.  ^ • 

r . , , . . » t '**. 

» - r ^ % *•  . ■ • . I • . 7:  ^ LV.i  JL  - - 


^>1. 


iiA-^  * ’ :ici.-'»C2 


.r  : *.: 


.,  > .v'i 


oo 


62 

of  the  basket.  Q,uoting  from  Musspratt’s  Chemical  Dictionary  refer- 
red to  above,  "In  the  pyritious  coal  localities  of  the  Vosges,  this 
process  has  been  practised  for  a considerable  period;  but  it  was 
not  adopted  in  other  collieries  till  about  1840  v;hen  it  was  intro- 
duced into  the  coal  districts  of  St.  Etienne  Rive  de  Gier  and  at 
Mens  and  Valenciennes".  Beckwith^  gives  the  ds.te  of  the  beginning 
of  hand-jigging  operations  at  St.  Etienne  as  1637.  The  first  Jigs 
used  for  coal  v/ashing  were  similar  in  action  to  that  described  by 
Agricola,  but  the  basket  was  made  larger  and  it  was  moved  up  and 
down  in  the  water  by  means  of  a hand  lever. 

Another  type  of  hand  Jig  which  is  nearly  as  old  as  the 
movable  sieve  Jig  is  shown  in  cross  section  in  Fig.  7.  This  Jig 
was  in  use  in  Germany  and  France  prior  to  1850^. 


Fig.  7 - Hand  Jig  used  in  France  and  Gomany  in  1850. 


^Loc.  cit. 

^From  an  unpublished  manuscript  by  S.  Stutz,  owned  by  PrO“ 
_fessor  H.  H.  Stoek. 


V 

. t 
, t ' 


'X  3 


M'- 


f 


oa‘i 


' o ' * 


,'w'X 


o-t 


V’l 


.^-.  v*»  01. 3X  x :i-  :'oo  -X  ■^iqo*..-.  j‘ 

'ioli  ?5  f'vi.l  :•  . oi.'*  . •'  Is6d  ••’  .-*  •'■•’  ' 

- • kvl^  Jt»3(0f/  . ‘•r- •>{ii;!->i>n3lsV  bru. 

. -'’'f  ti,h  . I rr:  ^ .-xofio  *^ . X:-":  i i 


. I * 


,.,:  i:j'  . 'i  ' ) i '■ 


' ■* .'  C 


?;  •'.  .'/V  X-30  0 *l>iX  />'■«;  j 

i - o.ij  , 'ooi'X 

' ..  . ■•.-•••'  ’ V ■'■•''•*  .:i’ _ .T>*'o,-, 

W.r.i  <si'.  > •■'  '>'[1*  ’-JOXjV 

V ^ 

fl  4*  .:yJ*J9ti  irwoi.  v I,  •'/..jXm  « 

• ■ i.f'' 

V.  % 

* A t ■ A 


j nc 


, /. 


63 


The  raw  coal  to  he  washed  was  placed  on  the  sieve  in  the 
front  compartment  of  the  box  and  the  piston  in  the  back  compartment 
was  jerked  up  and  down  by  means  of  the  hand  lever,  imparting  a puls- 
ing motion  to  the  water  which  jigs  the  coal  above  the  screen  and 
caused  it  to  stratify  with  the  refuse  in  a layer  immediately  above 
the  screen.  The  bars  shown  above  the  screen  in  the  washing  compart- 
ment were  to  guide  the  shovel  in  skiitmaing  off  the  washed  coal.  One 
man  produced  with  one  of  these  jigs  three-eighths  to  one-half  ton 
of  washed  coal  per  ten  hour  day, 

15,  Mechanically  Operated  Jip;s,  Stutz  describes  the  oper- 
ation of  a similar  piston  jig  in  is^ich  the  piston  was  operated  me- 
chanically, This  machine  was  in  operation  at  the  Besseges  Colliery 
in  1855,  One  man  tended  two  machines  skimming  off  the  washed  coal 
and  shoveling  in  the  raw  coal.  The  two  machines  produced  fifteen 
to  sixteen  tons  of  washed  coal  per  day.  The  ash  in  the  various 
products  is  given  as  follows: 

Raw  coal 21,35  per  cent 

V/ashed  coal 7,75  ” ” 

Refuse 71,65  « " 

Slime  in  jig  box.......  46,38  *’  '* 

The  refuse  contained  10  to  12  per  cent  of  coal,  the  slime 

25  to  30  per  cent  and  the  waste  water  2 to  4 per  cent, 

Stutz  describes  a number  of  similar  jigs  in  operation  at 

German  and  French  mines  between  1850  and  1860,  including  one  at  the 

Hirschbach  coking  plant  near  Saarbruch  for  vfashing  coking  slack 

from  the  Saar  district.  The  jigging  compartment  in  this  machine 

was  six  feet  long  by  four  feet  wide  and  handled  half  a ton  of  coal 

at  a charge,^ 

The  first  coal  washing  jigs  in  which  the  operation  was 
continuous  and  the  vmshed  coal  and  refuse  were  discharged  automatic- 


; T’  ■/  O ' 


J-'’  'J  L M 


\c  ^ »'  • :)  .*  ?r‘X^ 

' , . . • a^v; 


'i-.O  ■' 


n.' 


. tj 


1 ■: 


>c.-X 


ifi  • 


»Vvy  iTC, 


>1X0 


rl.vairrcJ'iiij  7?  5X3V.  "ju' 

- ^ , 


'i  n 


'*  ; 

'?  o>i(aj5f 


t I 


r 


O i 


64 

ally  were  the  Meynier  and  Berard  vrashers.  The  Lleynier  washer  was 
first  used  at  the  Brassac  Collieries  Puy-de-Dome,  France,  where  a 
plant  was  constructed  in  1854*  ^ The  pulsion  of  water  in  the  washing 
compartment  v/as  produced  by  a piston  pump  and  the  v/ashed  coal  and 
refuse  were  carried  out  at  the  front  of  the  v/ashing  compartment  by 
the  flow  of  water. 

The  Berard  washer  was  similar,  but  the  pulsion  was  pro- 
duced by  a piston  working  in  a cylindrical  compartment  of  the  wash- 
er. This  machine  was  exhibited  in  London  in  1851  and  in  Paris  in 
1855.  The  first  operating  plant  was  build  at  the  Mollieries  Col- 
liery in  1863. 

The  use  of  coal  washing  jigs  of  the  modern  type  may  be 
said  to  have  begun  with  the  introduction  of  the  Luhrig  jigs  and  the 
Luhrig  system  of  washing  in  1870.  In  1867  Mr.  C.  Luhrig^  of  Dresden 
Saxony  began  experimenting  with  the  Harz  jig,  which  had  been  used 
for  years  for  the  concentration  of  lead  ores  in  the  Harz  Mountains, 
and  in  a few  years  produced  the  Luhrig  coarse  coal  jig  and  the  Luh- 
rig fine  coal  jig.  These  or  similar  jigs  with  minor  changes  in  con- 
struction and  operation  are  the  most  commonly  used  coal  washers  at 
the  present  time. 

The  Luhrig  nut  coal  jig,  (Fig.  8)  consists  of  a rectangu- 
lar box  with  hopper  bottom  having  a partition  in  the  middle,  extend- 
ing about  half  way  down  from  the  top,  or  to  a point  sli^tly  above 
where  the  hoppering  begins.  Upon  one  side  of  this  partition,  is  a 
relatively  close-fitting  rectangular  piston  actuated  by  an  eccentric 

^S.  Stutz  Loc.  cit. 

^Jahrbuch  fur  Berg  and  Huttenwesen  1878,  p.  85. 


v:'«‘  •I?  /:,  -'*’  1.  ba  • I'  , . ^ 4 : 

, -'o.;.  •'^'  . -oi-*  . ' - ^ ".  j tTilXXoO. -*  J '■2*' 

ij;  , .--Ji  /r  'lo  oicXiJ.i  f , 'c*.3t  ni  '.'ir-.f  ..j  i • J.'tjsXs: 

6r,ii  r.-  ’ :'  ''  %■ -'  -•'»''u*  .■•-’■'»i*.:  -'.■  \J'  60:.  w'DOl-? 

" • 

s_ 

Cc;  - .qaiaD  eri  lo  :trto':  : ^ •'  > 

. r , ' V c ..  *t  f*  “ . 

f .'W  ,.  *‘«ia  'J'  I'l/itet’,  - -A 

;:r  '£cA  ^ n*N(S;j«xjsqp«*,_  ji r.:iv*iqit  ’'t.irr 

i . 

ci  i r.“_' ; iii  bii::  SCSI  .’.1  .sobnixi  Hi  . ■ •*•'>• 


ni:A?  : 

I 

J 

■>'^  ■ i H'f  3i.»»  Jr’Vli,  ’»:CT  - 


■-•x  ■' 


A ,t 


ftfis  *>0  •,:*:.  ^-.hx.iVh.;.  friT 


LW  :h;_;  ‘"it.  : ;:  n^Lf  t'J-iw  ‘.v-.u  o5  bi  • 

*lo  -.U-:;  ....  . ;-'o  a ,;.:  -rad-.t^tK  11  . 

'.1  r .w.  ■ .'  .; : ' -*■  ^ - ;■  .:^^r ' -ni ro^  -T  V-<« 


M.£ 


? I 


M V 


ctL'.i  'iJ  i ••  ■■'  ’ ' tP’i.i’* .;.  a nX  p- 

n.T’  ' ;uj*’  <??, i 'll  I "I'.J  w'.op...  . X“06. *4 >*.* » r^i  - 

irt'' .' .;o;)  . ''::J  /.r-.o  *: 'jct  : . *'•  -‘  .y^  • * .p  ox.^c.ri-^»i 

...  l'.a«.:r>i!l' 

!'•  ‘ O'li't  i'  iw'ii.i’j ■'  '■'  . * ( • '»  X*’ 0''  JfJti  y tT.M' L v.i.*. 

; i,-  .y-,  . .::  ,:oiUv  ^ . J - ■-  '..•:PVio4  * rff  t'^  XOi  ^ 

c/.  r .i;Tioq  r>  o.r  - , .■.>;  «ii..  mrob  '4^  Hi*!!:  •.rrro'^a 


-:•♦ 


it»  -y  ■ t 


’.i 


^ r:  : yi  ■ ‘ .iftor  /io:fniirtj  i.-''Xp'5rti4'tP- ’ -■  <olr, 


, i.  Py 


* 


66 


On  tl-ie  other  side  of  the  partition  there  is  a fixed  screen  which  is 
sometimes  sli^tly  inclined  away  from  the  partition.  The  jig  is 
filled  with  water,  to  which  the  piston  imparts  a pulsating  motion, 
forcing  it  up  and  down  throu^  the  screen.  Sized  rav:  nut  coal  is 
fed  upon  the  screen  near  the  partition  and  purified  "by  the  hindered 
settling  action  induced  hy  the  pulsation  of  the  water  throu^  the 
screen.  The  washed  coal  flows  from  the  top  of  the  screen  compart- 
ment at  the  opposite  end  from  the  feed,  i«hile  the  refuse  works  its 
way  across  and  is  discharged  throu^  a valve  just  above  the  screen 
and  below  the  washed  coal  overflow.  The  bed  is  kept  thin  enough  to 
permit  regular  and  even  pulsations  of  water  throu^  the  screen,  and 
thick  enou^  to  prevent  fine  coal  from  working  throu^  the  screen 
by  the  aid  of  suction  and  entering  the  hoppered  bottom,  or  hutch, 
of  the  jig.  The  refuse  which  collects  in  the  hutch  is  discharged 
at  intervals,  as  required,  through  a valve  at  the  bottom. 

The  Luhrig  fine  coal  jig,  (Pig.  9),  differs  from  the  nut 
coal  jig  in  three  important  particulars.  The  screen  is  horizontal 
or  slopes  toward  the  partition,  an  artificial  bed  of  feldspar  is 
provided,  and  all  the  refuse  passes  through  the  bed  and  screen  into 
the  hutch  from  vihich  it  discharges  continuously.  It  is  fed  with 
fine  coal  which  has  been  classified  in  a grading  box.  The  reversal 
in  slope  of  the  screen  is  for  the  purpose  of  bringing  the  thickest 
portion  of  the  bed  near  the  piston  v/here  the  rising  current  of  wa- 
ter is  strongest,  thus  equalizing  the  pulsations  throughout  the  bed. 

The  essential  feature  of  the  system  of  washing  introduced 
by  Mr.  Luhrig  was  the  screening  of  the  raw  coal  into  a great  number 
of  sizes  and  washing  each  size  separately.  In  the  discussion  of 
settling  ratios  of  coal  and  refuse,  it  was  pointed  out  that  if  the 


. ( 


1 J .r 


.'(J  ' 


j . 


1 


:i 


\-'>L-OS 


< 


ti 


I 


• » . .1  i. 

\ i :•  ;;i*c.r ; y.X  ■■jf 

^ ,:.:*  c.;i  - 


t 


» r 


• 


' 'jJ  ■ ■ , :^c;i. 


t 


« 


4 


J. 


t 


^4 


• j • : ' 


1 - . ' - 


•CJ. 


A 


/i 


; 


67 


iJ’ig.  9~  Luhrig  Fine  Coal  Jig 


60 


range  of  sizes  of  particles  in  the  raw  coal  being  washed  vms  too 
great  the  fine  refuse  and  the  coarse  coal  particles  would  not  be 
separated.  In  the  Luhrig  system  the  principle  of  sizing  before 
washing  was  carried  to  the  extreme,  on  the  theory  that  the  more 
nearly  of  a uniform  size  the  particles  in  the  raw  coal  are  made  the 
more  complete  will  be  the  separation. 

The  extreme  length  to  which  this  principle  was  carried 
out  in  the  early  Luhrig  washers  is  illustrated  by  a large  plant 
erected  in  1880  at  Reimsdorf  Colliery  near  Zwickau,  Saxony.  In 
this  plant,  as  described  by  Stutz,  the  raw  coal  was  separated  into 
nine  sizes,  and  each  size  washed  separately,  the  five  largest  sizes 
on  Liihrig  nut  coal  jigs  and  the  four  fine  sizes  on  fine  coal  jigs 
with  feldspar  beds. 


TABLE  5 

Sizes  of  Raw  Coal  Treated  At  the  Reimsdorf  Washer 


Product 

Number 

Size  Millimeters 

Equivalent  Size 
in  Inches 

1 

60 

to 

70 

2 3/8 

to 

2 3/4 

2 

45 

to 

60 

1 25/32 

to 

2 

3 

30 

to 

45 

1 3/16 

to 

1 25/32 

4 

15 

to 

30 

19/32 

to 

1 3/16 

5 

8 

to 

15 

5/16 

to 

19/32 

6 

7 

to 

8 

9/32 

to 

5/I6 

7 

5 

to 

7 

3/16 

to  9/32 

8 

2.  5 

to 

5 

3/32 

to 

3/16 

9 

0 

to 

2.  5 

0 

to 

3/32 

16.  Early  Development  of  Coal  Y/ashing  ^ America.  The 
first  record  of  any  activity  in  America  in  the  way  of  coal  washing 
was  the  granting  of  patent  No.  20756  to  Hezekiah  Bradford  of  Reading, 
Pennsylvania,  for  an  "Automatic  Coal  Jig”  called  the  Bradford  jig. 


30.*:  ' 

ili' 


.vi'i'a;'! 


.'X  -'.rue:- 


J 


B:ri 


r»i 


? • ri  'to  ae \q  m ’■;  • ' — 


r^on  'joIox'J  ^'  O'  1m>co  ->  'j..«'.o  wi'v  r':-'  ■^sry't'n:  5ri*t  9^'i'  “•x^j 


^i-<■  .*  ■ .^  ' '•  . *:JiJ  I 


w ^fT:.:tfJ:  -'./J  nl  . 

, •':•♦,*•.;  ^ li'  '.^;  i"i  ‘n 

Ijtoo '>•  T •■!  - rx  - t )‘Z}i  i ’•  J ? :.  i -^XiJin 

• ; ,r .'t fKf  u ..r  Qf  fWr,'.*''k  ■ "IT 

^’C-.'.r  ::  V<t  _ . ■ r = f [ i •:  ; 0:i.»  ■•■■ 

« . • 

• • j.  ■ ■•  ^■"  • ‘cO  'it-'-qr  i on' .-V:  C'l  .'  ;i  »»n . 

v‘  •-  • 1.'  ' <•  , ^^5f■ 

'\.^.:L  n^f'  , •’,>■.  '".'  w.  *.▼£«  f{'  . o , r , -ui-i  ■•'>  li  . 

'■ ' -c’  ■ 3^cJL'i  nrl  rro-i' r-  \ . icjo  ..■«.,  - .... 

. . . ~ , ; i.nq,^.?»X3'i 


“Ir 


t ti 

;yr.  X oJ 

. tKi 

'■-J'-.v’X  0’ 

■■xy  0^ 

' :'v^  oj 
<->:  <*t 

■:  0.* 


• 

a i-WV 

• 

i iOO  'l 

: ;.;XL 

’ i 'i 

< 

• ’*  * 

iii 

2\:.  V 

• 

. ' r 

I.' 

r 

X \\viS  X 

t X. 

''•• 

; ; 

i“j 

0.j 

cv 

Cr 

s'' 

OJ 

1 

V 

•x\. 

5^ 

y 

->>■■ 

C 

•»  f 

‘ ' { 

T 

\ 

3 • 

:i'v5  • 

„ ..% ..  . 

71 

r: 

*'  ‘ ^ » 

• 

0> 

O.t 

3 

Q -«■ 

S/  :-2  1 Vi  *....’ 

X'oo  "i  j •{: -?.•  ■'  •f  -J  ax  *:.^ ' 


■'.  fxx  ' . ^ r 4 


vrt 


'X. 


OJ 


* ’ V-.*  • 


..-1  OXi 


i. ' o v/  x>  X •/  ' • J «.ji  t **  . . ' *r 


69 

There  is  no  record  of  this  jig  being  used  in  coramercial  practice, 
however,  until  years  later,  about  1880,  when  an  improved  Bradford 
jig  was  used  in  several  anthracite  washeries*  The  first  actual  coal 
washing  operation^  in  America  was  probably  in  the  Pittsburg  dis- 
trict of  Pennsylvania  where  Jones  and  Laughlin  had  trough  washers 
in  operation  for  some  years  prior  to  1870. 

The  first  jig  washer^  of  which  any  record  is  available  was 
erected  in  1869  at  Alpsville,  Pennsylvania,  about  twenty-four  miles 
from  Pittsburg.  This  was  a small  plant  with  a capacity  of  about 
ten  tons  per  hour  intended  to  be  used  for  washing  coking  slack  from 
a group  of  nearby  mines.  It  was  erected  by  a German  engineer  named 
John  J.  Endres,  vfho  had  been  employed  on  similar  work  at  the  Prus- 
sian Government  mines. 

H.  H.  Stoek^  gives  the  date  of  the  beginning  of  anthracite 
v/ashing  in  America  as  187  5,  with  the  introduction  of  jigs  by  the 
Lehigh  Coal  and  Navigation  Company. 

In  1870^^  samples  of  coal  from  along  the  Pittsburgh  Railway 
in  the  Standard  field  of  Illinois  were  taken  to  Cologne,  Germany, 
and  subjected  to  extensive  washing  tests  v/ith  an  Osterspey  jig.  The 
results  secured  were  as  follows; 

Ash  % Sulfur  fo 

Raw  nut  coal. 15.  57  2.99 

7/ashed  coal 6.00  1.40 

Coke  from  washed  coal 10.00  1.02 

Yield  of  washed  coal  60^  to  65^  of  the  raw  coal. 

^TAIKE,  Vol.  3,  p.  77,  Discussion. 

^Process  of  Washing  Coal,  S.  Deischer  Proc.  Eng.  Soc.  W. 
Pa.  23-202,  May  21,  1907. 

^Editorial  in  Mines  and  Minerals,  Vol.  26,  p.  478. 

^Coal  Washing  in  Illinois,.  E.  E.  Meier,  E.  & M.  J.  22-88. 


f 


N. 


t 


< 


' 

1 


/ 

■A 


• K 


70 

These  results  were  secured  by  very  close  sizing  and  re- 
washing the  washed  coal.  Following  these  tests  an  Osterspey  jig 
washer  was  erected  in  East  St.  Louis  in  1870-1871  for  Adolphus  Meier 
& Company  to  wash  coal  for  coking.  The  Osterspey  jig  was  very  simi- 
lar to  the  Hartz  jig  from  which  the  Luhrig  jig  was  developed,  except 
that  it  was  provided  with  a differential  motion  to  give  a quick  down 
stroke  and  a slow  up  stroke  to  the  piston. 

During  1871  and  1872  Endres  erected  five  more  piston  jig 
washeries,  all  for  washing  coal  to  he  coked  in  a new  patented  form 
of  bee  hive  oven  called  the  Belgian  oven,  vrhich  was  being  v/idely 
introduced  at  that  time,  with  the  expectation  that  it  would  make 
possible  the  production  of  good  coke  froin  the  low  grade  non-coking 
coals  of  the  Middle  West.  One  of  these  washeries  was  built  at 
Eliza  furnaces,  Pittsburgli,  Pennsylvania,  one  at  Hollidayburg, 
Pennsylvania,  one  at  Irondale,  Ohio,  one  at  Equality,  Illinois,  and 
one  at  Joliet,  Illinois. 

During  the  same  period  a Berard  washer^  was  erected  at  the 
coke  plant  of  the  Johnstown  Iron  Works  at  Johnstown,  Pennsylvania, 
for  washing  coking  coal,  and  in  1873  another  of  the  same  type  was 
put  up  in  the  Broadtop  Region^  of  Pennsylvania  by  the  Kemble  Coal 
and  Iron  Company  for  v/ashing  coal  from  the  Kelly  seom.  This  period 
of  washery  building  in  the  East  and  Middle  V/est  was  brougjit  to  a 
close  and  operation  of  most  of  the  early  washers  v/ere  suspended  dur- 
ing the  panic  from  1873  to  1879,  during  which  time  the  best  Connels- 
ville  coke  sold  on  the  market  for  ninety  cents  per  ton. 

^TAIME,  May  1872,  p.  223,  Discussion  by  M.  Pechin. 

^Coal  Washing,  J.  Fulton,  T.  A.  I.  M.  E.  , Vol  3,  p.  72. 


-o_.. 


: '■■uu.'X. 


;■ 


1 i* 


■•  - c ■ 


71 

In  1875  the  practice  of  washing  coal  was  introduced  into 
the  Southern  field  with  the  construction  by  the  Eureka  Coal  and  Iron 
Company  at  Helena,  Alabama,  of  a Stutz  Jig  washer  to  wash  coal  for 
coking  in  thirty  Belgian  ovens,^  This  washer  is  said  to  have  been 
successful  and  was  dismantled  only  on  account  of  the  abandonment  of 
the  mine.  Due  to  the  hi,^  ash  in  the  Alabama  coals,  which  are  other 
wise  good  coking  coals,  washing  has  been  very  widely  adopted  in  this 
field.  In  1904  there  were  thirty- three  washers  in  operation  in  the 
state  with  a total  capacity  of  26,000  tons  per  day. 

With  the  return  of  prosperous  conditions  in  1879  a second 
period  of  washery  building  v/as  initiated  in  the  Eastern  and  Kiddle 
Western  fields  which  has  continued  down  to  the  present  time.  Be- 
fore 1885  five  more  washers  were  erected  in  Illinois  for  washing 
coal  for  coking,  but  none  were  successful  in  reducing  the  sulfur  suf- 
ficiently to  produce  a good  metallurgical  coke  and  all  the  washers 
built  in  Illinois  since  1885  have  been  for  the  purpose  of  washing 
coal  for  fuel  up  until  the  summer  of  1918  when  an  extensive  washing 
plant  was  erected  by  the  United  States  Fuel  Company  at  tiie  Middle- 
fork  mine  at  Benton,  Illinois,  for  washing  coal  to  be  used  for  cok- 
ing, mixed  with  a large  proportion  of  West  Virginia  and  Kentucky 
coking  coals. 

The  first  washer  erected  in  the  Rocky  Mountain  dis-,trict 
was  a Stutz  jig  washer  of  the  Colorado  Coal  and  Iron  Company  at  El 
More,  built  in  1881  to  wash  the  Engleville  coal.  After  several  years 
operation  this  washer  was  abandoned  because  the  waste  in  the  refuse 


^Coal  Washing  in  Alabama,  Ramsey  & Bowram,  Mines  and  Min- 
erals, Dec.  1904. 


V 


I 


72 


was  excessive  and  a coke  of  10  per  cent  ash  could  not  be  secured. 

In  1893  the  Colorado  Fuel  and  Iron  Company  conducted  tests  on  this 
coal  at  the  Luhrig  washery  of  the  Sloss  Coal  and  Iron  Company  at 
Birmingham,  Alabama,  but  the  results  were  disappointing  due  to  the 
hi^  proportion  of  bone  coal.  An  experimental  Campbell  table  washer 
was  then  installed  and  operated  for  several  months  and  was  found  to 
do  good  work,  but  at  too  small  a capacity,  A Forrester  jig  was  then 
installed  in  the  experimental  washer  and  tests  were  made  with  such 
success  that  a Forrester  washer  was  erected  at  Sopris  in  1896, 

The  first  Luhrig  washer  in  America  was  erected  at  Birming- 
ham in  1890,  and  in  the  ten  years  following  six  other  washers  using 
the  Luhrig  system  were  erected  in  ^erica  at  Carterville,  Illinois; 
Belt,  Montana;  Be  Soto,  Illinois;  Dunsmuir,  Vancouver;  and  two  near 
Greensburg,  Pennsylvania.  These  washers,  however,  were  not  very 
successful  in  America  due  to  the  difficulty  of  operating  such  a com- 
plicated plant  with  the  unskilled  help  usually  available  here.  A 
wide  spread  prejudice  against  the  practice  of  washing  coal  in  gen- 
eral, which  grew  up  during  this  period  and  remains  more  or  less  to 
the  present  time,  was  engendered  very  largely  by  the  great  diffi-  I 
culties  and  losses  encountered  in  operating  the  ea.rly  Luhrig  plants 
in  which  the  principle  of  close  sizing  was  carried  to  a ridiculous 
extreme.  The  great  number  of  screens,  classifiers,  elevators,  con- 
veyors, bins  and  jigs  necessary  in  order  to  handle  the  various 
sizes  separately  necessitated  a large  capital  expenditure  and,  in 
an  attempt  to  economize,  the  individual  machines  were  usually  made 
too  small  and  were  crowded  together  in  light  wooden  buildings  three 
or  four  stories  hi^,  so  that  the  plant  presented  the  appearance  of 
an  intricate  maze  of  elevators,  conveyors,  belts  and  shafting,  whicl: 


'■  * ' ( I OO  V ' ‘ 


• 'J''  cC.'  '.i  I r ‘v  Xi.’  c 

)J  cu*j  «itJ  .1  ^:, 

ir  V ; 


1 ' . 


% 'c;  OT.  ~ii.\  : 

} 

^ ■ 7 ' ^ 9ti$ 

^ — ; • ■ i ;»■  i • ' '■  '■  ■ : ■'  i>  1: 

f 1-  • . . -,.'1  on^  . = , ^ .licrx: 

n . • >o  t»  to.ioiq  .r. : 

~o:  Ao^c  -.■'f-: — A-f.-;;  - : : rj  , 

^ i v.iv*,iA  ooj  ^ v "*  , c 


*1  -I 


V'  Gj 
' 


t 


> r- 


VI" 


M-T'Itj-  liTi.-fj. ; -.i.' 

■■  k. 


V J 


V » . 


V O 


73 


furnished  numerous  opportunities  for  disagreeable  break-downs*  The 
complication  of  design  was  further  added  to  by  the  machinery  manu- 
facturing companies  who  built  the  plants,  as  they  v/ere  naturally 
desirous  of  disposing  of  as  much  of  their  machinery  as  possible. 

\7hile  the  Luhrig  nut  coal  and  fine  coal  jigs  or  similar 
machines  are  still  the  most  commonly  used  form  of  coal  washer  the 
complicated  Luhrig  type  of  washing  plant  has  gone  out  of  use.  It 
has  been  found  that  the  laborious  separation  of  the  coal  into  eiglit 
or  ten  sizes  is  unnecessary  and  undesirable.  The  most  common  prac- 
tice at  modern  -American  washers  for  coking  coal  is  to  screen  the 
.raw  coal  into  only  two  sizes,  or  at  most  three  sizes  before  washing, 
and  at  many  washers  preparing  coal  for  fuel  screenings  ranging  from 
three  inches  in  size  to  dust  are  washed  together  in  one  jig  v;ith 
satisfactory  results. 


m.n  fi-,  f,  ‘ 

’ ^ ' I • • . . ^ 


\ ' • 


nt-j<f  j V 


#*► , - t / 

. %*-*  4^  1 Aw 


•.  1... 


I ''4  - t>r*o  .tJ  I'O 

- - ’ .-.'L-rco 


1^,'.'}  'i.i 

•is 

I 


t Cn: 


L 1. 


‘ .'■  I 19  «■•  i 


2.  . . 


tc  £-Ci*riec 


■0:iX  •■ 


’■■'.i  -‘''.-w  oi.r- 


l^adlfpT’  rt?oo'  r, 


ismoir.'  . ..  i 

'U  .u;.  ‘vX'i-v'hr r.  ' .v'  ;:I  r*iv'  • 

-'*  < .irrcibo;j. o;,: 


a 


■5  ' ' CF^‘  wx,;ri  lAoo 


•<’'  ■ 1;' 


r^ri^ 


74- 


chapter  V 

MODERH  COAL  WASHIHG  MACHIHSRY 
^7.  Jig3 . Althou^  a number  of  new  developments  in  coal 

I 

Y/ashing  machinery  have  been  introduced  in  recent  years,  the  jig,  in 
one  form  or  another,  still  remains  by  far  the  most  coimnonly  used 
form  of  coal  v/aslier  and  will  probably  continue  to  be  because  it  is 
the  only  method  which  has  proven  entirely  successful  for  v/ashing 
coal  of  the  fuel  sizes. 

It  is  safe  to  say  that,  in  America  at  least,  more  coal  is 
washed  on  jigs  than  on  all  other  kinds  of  washers  combined.  The 
fine  size  to  v;hich  coal  has  to  be  crushed  for  treatment  on  concen- 
trating tables  eliminates  these  machines  from  consideration  for 
washing  coal  for  fuel  except  as  auxiliary  equipment  for  cleaning 
the  fines. 

PRINCIPLES  OP  JIGGING 

The  jig  is  esseni tally  a perforated  plate  or  screen  sup- 
ported in  a horizontal  position  with  an  intermittent  pulsating  cur- 
rent of  water  flowing  through  it.  On  the  downward  stroke  of  the 
plunger,  the  water  is  forced  upward  tlirough  the  screen  to  a height 
of  from  six  to  twelve  inches  above  tiie  screen.  On  the  upstroke  of 
the  piston  this  water  flows  back  through  the  screen  by  gravity  or 
is  drawn  down  by  the  suction  of  the  piston.  This  cycle  is  completed 
from  eighty  to  one  hundred  fiftj^  times  per  minute  depending  on  the 
size  of  coal  being  treated. 


..  • : o*;  Mvq  40-!  ''  Joi 

'■  •<J  0 TmI  ' :j  , i 9Vj  - ■ 

ji'^v  '/v:'  7 z^..  " 


t •, 


I 


75 


A bed  of  raw  coal  several  inches  thick  is  maintained  on 
the  screen.  On  the  upward  flow  of  the  water  the  coal  particles,  be- 
ing lighter  than  the  refuse  particles,  are  carried  higher,  thus 
tending  to  separate  from  the  refuse  in  a layer  above  it.  On  the  re- 
turn downward  flow  of  the  water  the  heavy  refuse  particles  will  fall 
more  rapidly  than  the  coal,  thus  increasing  the  separation.  V/hen 
this  action  is  repeated  a sufficient  number  of  times  the  coal  and 
the  refuse  are  arranged  in  definite  distinct  layers  on  the  screen, 
the  coal  above  the  refuse. 

As  explained  in  the  chapter  on  fundamentals  of  coal  wash- 
ing this  separating  action  of  the  jig  depends  upon  the  operation  of 
Rittinger’s  law  of  the  rate  of  falling  of  particles  in  water. 

V = cfs  (S-1) 

From  this  law  the  maximum  range  of  sizes  of  particles  that  may  be 
successfully  treated  together  is  derived.  It  was  early  observed, 
however,  that  in  actual  practice  a much  wider  range  of  sizes  could 
be  treated  successfully  than  was  theoretically  possible,  according 
to  the  free  settling  ratios.  Several  theories  have  been  advanced  to 
explain  this. 

Rittinger  ascribed  this  excess  jigging  power  to  the  fact 
that  a small  particle  of  the  heavier  mineral  is  accelerated  more 
rapidly  than  an  equal  settling  larger  particle  of  the  lighter  min- 
eral. A particle  of  pyrite  for  instance  may  attain  its  maximum 
falling  velocity  in  one-tenth  the  distance  required  by  the  coal. 

In  the  succession  of  short  falls  produced  in  the  jig  this  would  have 
an  important  bearing.  As  the  limiting  velocity  would  probably  not 
be  attained  by  any  of  the  particles,  the  rate  of  acceleration  would 
largely  determine  the  separation. 


t -j  ^ ' 


V^  'S  i»0:5  ' ."T.  ' 

i 

v'ci-  -jr"'  t>'  .nov'it-in 


, f-.ii'  L*:- 1 -j  ■?»cir‘tol  .^r(?  - j 'XOw^ij'll  jni 

•.  *'*.  9^  . . " .rv'i  .1  oiJi  moil:  . 2 c«;  :■  Tlbno.. 

X^.  ;'  ^ 1 -•  vv.,-»i.  ‘?o:?  - ' Ic  .•■:L^  ^*i■/•:.'^’o^ 

'"  . Sfiv‘  gniy  :"•  '.-L  . , V \/*‘i  -'-i.  ’^'?v 

--•■•-  ■'  •'  * ^ ..-.r.i  . . i woi«.'-'T91  ai  fTC  1 ; 2®  S j ; 

s nc  r'c-'*v--i-!  Jj.'iisi'.  ‘ ■'i'  I 'l^f' ''lo*!; 

» t/loi  ' ■ ; Tnoo  ©*.;j 

— ' . • /'' 

•7  J ' ;-  . 'j.w"'  ,:o  t'‘*  :^;(o  ■ . ;.,.  ...  'i.jqx- 

"iv  : i ', . T '*  ^ , to  noi.? 0^  ^niJfi.  ..  -.Irtt  p_.il 

. -.  jc'  .:i  , : V :»o  tv  '••I.T  3"*  ic  vroj.  ' ^ 


.*  .‘I:  ..  ■•*  . r«»  £3  >j  D.-."  .1  g„U  CrClU 

, ov  -'0  c-^-  r i v:  il: '**, o.^  . :‘ii  vIIi;t«a9p-qro 

X;.o:)  r .•...•  ') . ■r*'.  . iv.'  ..jv.'T  j:  Iij;fJr)i.  ^ 


c: 

* 

'"‘lx  .•  ' ' ' ^*;':v,’  - vX  ‘"J -:^on 

w 

OcOit-iVd  : .V.  ^•-.'  ■?•/■  J 

• I -ov.-v  xv-roT*?-  .,.i7Ai  i.J- J“i>- 

■ "'£  ■;.■>  Ov 

4 

■ri7  . 

J 

v-.t  "‘'it  ot  I'-r.  uq  ;■ 

; .'6 '>2Xf>  •■i  *c  bou'i’ZMiiT  * 

^ *r 

<*.4  4 

■J  r •.  ■.•  ■•  •:-:v...H,{  It  r>Xt'XXi  •' 

I. ’..'rra  « 

> 


. 1*  f' 


’•>  £ :;r  nljiiltu 

* :■*:  Oiilf  *4i  boiXjjp 

V:  ’ n L}  j.  UOX  •^  * • " • , ;■  e .it 
/ 

^ 0*X  .-J  _L  JU  0^‘7 

. .'i'V  j‘.;''.3X;10v-i  ‘£t:' 


ViV^  *:■■.  3^xr.Xi  tv  - ^ 

r>*:  V L'-i  - .iO  rri  Xo rlor  j oiX/?': 

.\x  i;vOiX'0"t'r  2II  ' X':drfe  -to  .'  oli^n^^^oouz  nX 

ofi?  .BA.  . t.-.  Xuovi'i  fi  • 

, 6.  • ; orfi  vii>;  x'f  d' 

* '1 -rjoa  ■•’-fj  f?:liiaiO^ 


76 


Later  investigators  designated  as  “hindered  settling”  the 
fall  of  particles  enmass  under  the  conditions  existing  in  actual 
jigging  practice  where  the  free  fall  of  individual  particles  is  hin- 
dered by  immediate  contact  with  other  particles.  The  hindered  set- 
tling ratio  is,  as  demonstrated  by  commercial  jigging  practice, 
larger  tha,n  the  free  settling  ratio  of  the  same  minerals.  Professor 
Henry  Louis^  explains  this  as  due  to  the  fact  that  the  small  parti- 
cles of  the  heavy  mineral  which,  by  the  free  settling  ratio,  would 
settle  at  the  same  rate  as  the  larger  particles  of  the  lighter  min- 
eral, being  much  smaller  than  the  equal  settling  li^^t  particles  can 
slip  throu^  the  interstices  between  the  large  particles  and  may 
therefore  settle  with  less  interference.  Professor  R.  H.  Richards^ 
considers  the  falling  of  particles  under  hindered  settling  condi- 
tions  as  equivalent  to  free  settling  in  a medium  which  is  heavier 
than  water  as  each  individual  particle  must  settle  throu^  a medium 
made  up  of  all  the  other  particles  suspended  in  water. 

A third  idea  advanced  by  Professor  H.  S.  Munroe  explains 
the  large  ratio  of  sizes  th^  can  be  jigged  as  due  to  the  effect  of 
interstitial  currents  on  the  small  particles.  By  experiments  with 
particles  falling  through  v/ater  in  glass  tubes,  Munroe  came  to  the 
conclusion  that  the  rate  of  fall  in  restricted  channels  was  alto- 
gether different  from  free  settling  and  obtained  an  experimental 
settling  ratio  of  1;30  for  galena  and  quartz  under  these  conditions 
as  compared  with  1:4  for  free  settling  conditions  by  the  Rittinger 
formula.  Richards  checked  this  value  by  dropping  a mixture  of 

^The  Dressing  of  Minerals. 

^Text  Book  of  Ore  Dressing,  p.  268. 


•f 

t' 

.1  anoij-  ‘•  •V  •:  > ,.t<  OQiur.r.o  e '*  ,.  ^.y; 

1 

1 j ' r>«r, 

- : • f v..i : . - - i: : • -ti.  . v‘o--J;iao  e*>.±,  • :*.-v:J.  vc! 

, t 'c:.+  •x.t.'jiiota»b  ' , - >ini.L 

- . '■  ':-.  :r  f'-.r  r ciJ  * ;■  i ; 

- , * ^ XI  ,^  •:  . ‘;  * ■}  It  n . a/:irXqxfli  I 'v'  X 

i':uo^  ivt  ^7;;or'  vj  “tv  '^rl' 

- ,i..'  :.  ■'  o o.it  2^  ■*••  ai.i:.u  .•  .»  ;a  -)!>r*^se 

1 f • !'o.'-^  *!..:•;  J ...  ii  ;;  layoff  ’^rf*  '.•/  t '^Xl-JBr  J -’-a  , 2^ 

•'  r . ;,;i.  ^ i-  . C I ■* '’  cooiw*p*'. •< J ' ■.  ' icjiatiC  .-/.i'-i 

1.  r'-i'  ► ' *”  'iO'  .\iti;'i  4 ^T’' ^'tcJ  ri  «M£i  '.'♦i'.v 

--  ■- - -.'4  w.;-£2'7.l2'  ' f':^  :•  aoXolv'nv;  I-'  - orj /a'u-jiii^irxoo 

i •.*"  • -i::  • V rl  gi-fx' *'*£;r  ■'••  . it„.,'..:.vi.;/f  ^ ;j-  a^.'!-- 

P:i;i^'i.:i  ; .,-.<-X''i  ‘ o_  . t . ' v '•  jisJ-i  j\  ifi.tj  . j : '^  '£'  vv;’7  ni;r”j 

. .'  ••  -li  ■ •,.-••'»  "oiiic.'?  lortxfo  ! ' IX.'.  . (ja  .* 

9 

r ' i „ I . ’.r  , . CC;',  dO’t Oli  vj  O .' • ■ rTclViJS  2s6i  ixi#  i; 


r w X ■ . ■•  •?  : 


.'./I-  I :i'i  • ' 
Aj  O*'  - . 2 


. I«  ■-'.■£??  .TO  *J  1 

. :•*  V.-  :I,;;o;i  •:?,  v,i  _.r. ! 


€:;tjil  0 J 
17  .L,? 


-o.  I ...V”  £lo-:i'j.  if'Ioi.'T.’  -O':,  i **  to  e^2'i  .: 
C :I  ^ I -I — : ft  '»«p.x'-I;o  lirr;.,;  i^rilJJ-r  . oom  1 ■••'!: 

er;Oj. li::  : .o  700,  .■*  'ivL'ftr?  ryoi:  oJ'  ,ri  i.'/t  OS:' 


‘ .»  oil  i;cil  r;.-.'- 

•iif.2  wii'-  (.■•' 

iO  r':;.:T  ';  CV  ^ 

. J i yT‘  ^ _ *'■  i: 


» 

> V 


2'£  y*  X ; 


. : i 7q  O'f.  - ',*,'1  n t : i . , •.'  , ; .r  ;\j  h -. 


lotH  ifi'-’ •fxi/ro'’: 


\ 


A 


liOqOTl  . 'iO  t 


Hgp  aexiiBsttas-r^,--  . . 

? ‘i 


,4f‘- 


f» 


f 


77 


small  galena  and  quartz  particles  throu^  a slowly  rising  current 
of  water  in  a device  which  he  called  the  pointed  tube.  This  had  a 
narrov:  section  at  the  bottom.  Screening  tests  were  made  on  the  ma- 
terial which  settled  throu^  this  narrow  portion  of  the  tube  into  a 
rubber  bulb  below.  The  ratio  of  the  average  sizes  of  galena  and 
quartz  found  together  in  the  bulb  was  1:6.  The  interstitial  ratio 
for  shale  and  coal  if  increased  over  the  free  settling  ratio  in  the 
same  proportion  would  be  1:9  where  the  free  settling  ratio  is  1:6. 

The  effect  of  the  interstitial  currents  is  operative  on 
the  down-flow  of  the  current  as  well  as  tlie  up- flow  and  where  suc- 
tion is  used  drawing  the  water  down  through  the  bed  by  the  return 
stroke  of  the  piston  a classification  of  the  fine  particles  will  be 
effected  in  the  interstices  of  the  bed  of  material  on  the  screen. 

. This  is  born  out  in  practice  as  it  is  a demonstrated  fact  that  a 

A 

natural  feed  of  unsized  coal  is  washed  more  effectively  on  a jig  in 
which  moderate  suction  is  used,  than  on  one  vhich  is  especially  de- 
signed with  valves  in  the  piston  or  a differential  piston  actuating 
mechanism  to  eliminate  suction.  On  the  other  hand  if  closely  sized 
coal  is  treated  on  a jig  with  suction  on  the  return  stroke  of  the 
piston,  the  tendency  is  for  the  particles  to  arrange  themselves  in 
reverse  order  from  that  desired.  The  coal  particles  being  of  small- 
er inertia  than  the  refuse  are  more  readily  reversed  in  direction  at 
the  end  of  the  up- stroke  and  are  consequently  drawn  to  the  screen 
ahead  of  the  refuse  by  the  suction  of  the  return  stroke. 

In  order  to  utilize  the  effect  of  interstitial  currents 
in  jigging  closely  sized  fine  coal  a permanent  artificial  bed  of 
coarse  material  is  sometimes  placed  on  the  screen  of  the  jig.  This 
a-cts  in  the  same  manner  as  the  shale  bed  accumulated  in  jigging  an 


£ 


‘ ^ ' ■•  ^ ..  ' r ■■  .;‘*i.-  hfti. 

» ’ *■  I*  ■'-.*■  tiX  cr  -1  ' :J  ■■  'rXiOv  ' ■■'  r'’r>ifit»  ! 'y.Tjt?K  "Xj 

..-  r.iq  -.j  «jt?  J •;  (!<■:!.  - 

;i  : , ^»cin<;rt  J oa  ■ CaiteJ 

‘■,.  -■  ■'N;.  •'•  .r.  • .*•  ■■  . ; jLb  ■ .iliid’ ■ r^rfirx 


C.-iJ; 


; : - 


. : ;'  \id  o.^>l  :i  L 'UOi 

- 2J:..  .1 ‘•■>u  O':’':"  - / "tovo  IJ;  l3DS  '*n  :r o' 


♦ . A a V 


.10  0/ 


•i 


\ii  ni’r.  >*t.‘f'.  j 


!•:  ■ V*  t'T  ••  '■ 


■ .'-..'i  vj  -I-,  i ••  :..v7;-ti..5  -'10  \ cwu  / 

■'<>;'  i :,•<  r.-  0 i:ui'  ’’■.i: 0,.^ari  n;  r.ox.: 

'v*-' '■••'-I:  fiJ  ':  :;o.c  £ n '■J::;  i cj  o.-C*;  ; 

■ r^c  iiiv-j*.'!  ;c  fc'i  ; (^(i.  1 -;■  ;.  t oU*  •' • : tti 


j'j'-  - A>  ri 

e no  ••:  -.•>  i : .'■‘‘■'‘Is 

--  I V,.r  ■ J.U ' 'J  tr.  : 0.;:;  , O r. 

•'..ci;s.‘...>'X"’'-’i ii'  c 
’j'OSXn  *.X  il  ■’  r !^;r,<'i!  'I  •<*.'.  9f'* 

;*■  . ‘'.o  '*  : ofiJ  ao  i . 


i 2 •-"  .rJt;-  . - ; L'C  i ai 

, ^,r  ai  rJ-'-'i'^nom  rfojtxX'’ 

.•  .'  Xoi--  aJ:'cG~T.:v 

♦ ; ...j  'nia>?rfo  '.■ 

......  ■•■'J  f •.;  n I f.  nu 


■ :L  . •; . - v:;- 1 fe.'*  ^ i*:  OJ  . . ‘ui  lo')  -,'i  vy^j-arte  '*'  I’.'O  , 

fX  ■•,'  ij  i ni-.  ' tidily/ ■5:;  1.  .300  srH  .♦>' *fi  1'=}^;  *,:  *.'1  0““»V0'i 

iiy.;  X ri*3'..J;'j  ri  h>i  ':£j:'  cy'C  oaoci  e'l.a  oajJ'i -•■-  ? i*  . rf.'i:  •i-t's'rai  a: 

• - .-  ■] 


‘ . ••;  i 3 : arit  ncif  oi/:{  ®Jut  '.„j 

•s:’ no'i'H/y  ri  .: .?  r.-;  . -i  'i.;  .ry?-  To  Cli:*  TxiLldi/  t-c^hiv  ,al 

'-Q  1 .iJ':a  y.  . 'i «.  f -.co  a fi . ijor.ia  ^IbsoIc  ' i:v,  - '.  ril 

; . ■ cr 

> ' "iy  I’c  .•*:l''j  r a.  j ..'■•■  a-Xq  ri  X».i'..'’:  ■ o^'Xr.oo 

’ .:.;•  .*  XLr'rif.oo«'i3  -X  '.>X#!V.s  Oiii  '.1.  '•fortaa:  . ~ oa.‘  ri''_ 


78 


unsized  feed.  The  fine  refuse  is  drawn  throu^  the  interstices  of 
the  bed  into  the  lower  part  of  the  jig  called  the  hutch.  The  mater- 
ial used  for  a bed  is  usually  crushed  feldspar  having  a specific 
gravity  of  2,6  or  about  the  same  as  shale.  This  method  was  intro- 
duced with  the  Luhrig  system  in  187  5 and  is  vridely  used  at  the  pres- 
ent time  for  fine  coal  jigging. 

During  recent  years  great  progress  has  been  made  in  jig- 
ging practice  from  the  viewpoint  of  capacity  and  economy  of  opera- 
tion, Very  large  plunger  jigs  of  sixty  to  seventy-five  tons  per 
hour  capacity  are  now  used  successfully  and  the  cost  of  jigging 
coal  has  been  reduced  in  well  managed  plants  to  very  low  figures. 

The  main  features  of  jig  design  a,nd  operation  remain  practically 
the  same  as  at  the  first  American  plants  built  in  1870  and  probably 
nothing  in  the  way  of  an  improvement  has  been  added  which  apprecia- 
bly increases  the  effectiveness  of  the  operation  so  far  as  cleaning 
the  coal  is  concerned. 

JIGS  IN  PRESEL^T  USE 

Generally  speaking,  the  piston  jigs  in  present  use  are 
similar  to  the  Luhrig  jigs  already  described.  The  mechanical  dif- 
ferences in  the  various  makes  are  usually  in  the  method  of  piston 
operation  or  of  refuse  discharge.  The  Lehi^,  Forrester,  Foust, 
Shepard  and  Coppee  jigs  are  operated  like  the  Luhrig  by  a simple 
eccentric  motion  which  gives  equal  up  and  dov/n  movements  of  the 
piston. 

The  Elmore  or  New  Centui^'  jig  and  the  Baum  jig  aim  to  pro- 
and  slow  up- stroke 

duce  a quick  down-s troke^ to  reduce  the  effect  of  suction  in  the 
jigging  compartment  on  the  return  stroke.  In  the  Elmore  jig,  this  is 
accomplished  by  means  of  a cam  on  the  eccentric  and  a strong  spring 


?.  1 £>  .r 


I 


& 

oe-iij 


•'  ' 

- N'  CO .' 

r 

» 

f 

' ^ . 

I ' 

0' 

a a; 

t 

e. 


'rfsac'iaV 


L.' 


^ ■t: 


i V 


i l‘TiI.,0  j.  U Jir  ■ toa^i  - 

.V* 

i XG:  . , 1-  'r  r ai  hoc 


sni  t : 

X/.I 


.>C. ''.r  .-L'  . 


.C'O'  '■  ■ / ■ -.'OA  H . -J  lY'Z' 

•:  *;.  rto.t-:r.;  ©rfJ  u'cTlW  . 


■’  'A* 

I o'  XI  i.o^sf  fiAi'j  ^ -i«o\  :u..'rr/r 

— ■ ■ * . ^ ' 

:c»  xpf}‘\ooe  b,’  . 'jlo>*q^^o  t ^ ■},•:.  -,tv  t'i 

ol  evl’t-x-^a-  ■ :'  0^  V v i i^  T*:_;  -a':*:  ■ •:'i  >.' 

• '•''^-  ' - '*  V L ' - ' •'»■.'  i'u.^tf  VO  oi:.‘  i o‘jof"'o 


-■-ir  xcr 

v;*c '■•’'■  ■ . ,'  .j  ,!.<j 

.'ftrt-  .1“  j|l 

h'^D.UfcO't  SOO'J  nod  X ICO 

^ - - i J 0,  •'tq 

:.  ■ / : . - 

“ * ' ' u‘ , .i.c:9'j  •-  .1 

-»„ 

'to  .qX ■»:.*.  0 T 

- 0 

■'':U  ai  *•  ? 

0 £t»o*  *^:a. 

10  C'lv*  i'll  a»:i:  .' 

V . ' *■-  u 

1 f'o  :’.  '‘i**(7C  . 

-*■  „ u:  ■ '-.O'  t^r< 

- ■ "t  j / U<Sei"0  :j  1 

. ^rrteD  i-o  Ifi.rt  ■o;..,* 

t' ' r 

* ‘ • H • V X W 

j % 

'.'  !^n.:  it.iO'-iouq'  frr 


. r* 


-I  •’r^Ln.-:  0!)m  or 


0^'^.^  YI.J  G.'Mif. 


li 


T 

'i  ^ 


•; 


(■•'  ij  >-jr^or.1  Oi'-i  . 1 ',«mTb '.?B,C/  0‘iSj  ^r^^i,-.,  1 n;  ■ O.l "}.  tiT*  '^r*‘  i Ba  Oils*! 

* o'i--  '.''  , . : ' ;T  . V f»8A;‘iox  Iz^  v •'  . .':.  .-p 

M ‘♦.u  9Ali  'ooj  Ti-}.  ' i t '>‘v‘;.toO  or-:  -Ci 

r.v-  ^ ;,r:  o;ia  qi.*  I.vpo  {oiiiw  iUUJOiu  i * ac- 


( 


->0,'  \;;xirfr,?>:  ••  • - 'J'tawix.  :9<J 

o;.'ox-  I -i{;’ 

:u:x  *o-  1'..  t'.'j*  io;iiv<»x  c ' 'a'i' i ^'Oiwj 

# 

G • I - C,:  :-,r  J-  ,:7.  , TtCxJ,-  nr!^  m J .'. o’*r^ *ie^- c 


sic 


C 


«o  ,a>o  r 


79 


v;hich  makes  the  rider  follovr  the  ccm  closely.  In  the  Eaum  jig  com- 
pressed air  is  used  to  produce  the  pulsation  of  the  v/ater  in  the 
jigging  compartment. 

Probably  the  newest  jig  of  this  class  is  the  Pittsburg 
piston  jig  used  at  the  Middlefork  vrashery  of  the  United  States  Sted. 
Company  at  Benton,  Illinois.  In  this  jig  the  piston  is  horizontal 
and  double  acting,  working  in  a vertical  partition  below  the  middle 
of  the  jigging  compartment.  The  effect  of  this  is  to  give  an  up- 
wart  current  in  one-half  of  the  jigging  compartment  cind  a downward 
current  in  the  other  half. 

Any  of  the  piston  jigs  may  be  and  are  used  v/ith  artifi- 
cial beds  of  feldspar  for  fine  coal  treatment  as  in  the  Luhrig  fine 
- coal  jigs. 

The  most  v/idely  used  of  the  movable  sieve  jigs  are  the 
Stewart,  Shannon,  iiraerican  and  the  original  Pittsburg  jig*  The 
Stewart  jig  is  commonly  used  at  Illinois  washers.  The  characteris- 
tic feature  of  this  jig  is  the  basket  or  box  with  perforated  bottom 
into  v/hich  the  material  to  be  washed  is  fed  and  over  which  the  cur- 
rent of  water  carries  it.  The  entire  box  is  suspended  in  a tank  of 
water  from  eccentric  suspension  rods,  which  impa.rt  to  it  an  upward 
and  downward  movement.  This  forces  the  vrater  alternately  bs-ck  and 
forth  through  the  perforated  bottom,  lifting  the  coal  and  allowing 
it  to  be  carried  away  by  the  stream  of  vmter  flowing  from  the  top, 
while  the  heavier  material  or  refuse  settles  on  the  screen  plate, 
from  which  it  works  forward  and  off  into  the  water  tank  through  a 
valve  set  at  suitable  height. 

The  Pittsburgh  pan  jig  differs  from  the  Stewart  in  Uiat 
instead  of  eccentrics  a crank  arm  mechanism  is  used  in  order  to 


80 

produce  a quick  dov/n-stroke  with  a slow  up-stroke  and  suction  in 
the  hed  is  still  further  reduced  by  extending  the  sides  of  the  pan 
belov/  the  screen  and  inserting  a solid  bottom  with  valves  which 
open  upward,  but  close  on  down  stroke  preventing  the  water  in  the 
pan  from  rushing  out  through  the  screen. 

The  movable  sieve  jigs  are  most  suitable  for  coarse  coal 
and  for  the  production  of  two  products  only,  as  in  order  to  produce 
a third  or  middling  product  two  jigs  v^culd  have  to  be  used.  Por 
these  reasons  their  use  is  confined  largely  to  the  washing  of  coal 
for  fuel  where  a large  tonnage  of  unsized  coal  is  to  be  cleaned  of 
only  the  large  pieces  of  clean  refuse;  although  v/hen  the  Stewart 
jigs  were  first  introduced  a large  number  of  these  v/asheries  were 
built  in  the  south  for  v;ashing  coking  coals, 

A number  of  the  jigs  described  are  illustrated  in  Pig. 
lof  and  classified  as  to  method  of  operation  in  Table  6. 

^Prom  the  files  of  the  Department  of  Mining  Engineering, 
University  of  Illinois. 


. . 7~  \ ..  . 

v; 


4 hoot-; 

M 


K 


«k 

.V  . 

- Sj'^yo  X!-t3  o ‘.'  ^ '.  t lie ',' , 


r.:(  C:; 


o. 

‘^V  i 

cJ-  -X'^6i-o 

n.*- 

t . 

; . ; . vj  Xq  {•> 

.1  c 

. '-' i J DU'.  O t.i  J 

. • i 

V.-  4.. 

.. 

. j . .1 1 (jwj 

V -..n. 

Jt*“ 

■Sj 

1 ' ‘ - 

- i.  -j  '.  . / . 05 

(fiJ  J-  . . "f* 

j : , ■ ■ 

ii  ■ 

«104  ./ 

>* 

. vf  fJU  I'i 

, t 

. , ■« 

.'  ",  -. 

'to 

i'f.Ol'J  - 

« 

' 

t 

■ ' : -.  v.Jcr>  \.  1 

.••  .iV 

•ir.  ; .'CJuor  ‘ 4.'..’j 

■ ■ r 

^>9  J ^ . 

' f.i,  '*r 

W • *•' 

* '’  4 ' 

, •;  . ,•  i 

.-.•1  _ c ‘ 

0 

^ai;. 


I .. 


‘i  f’L'^  0 


‘-'J. 


• ' T'^ii..  i If;  , '.•.w  1( 


4 


81 


Elliot  Trough  Y/aslier 


Stewart  Jig 


i^’ig,  10  - Types  of  Washers  in  Present  Use 


•S.  ' -y» . 


^ r ~ : ‘ ■; 

* ’ I • 1 

,'yv,  -i  M , 

« ^1p  i * ',  ‘ • 


.f.* 


^ ,,>y  i ♦ 

^ /•  •V,T  ^ ' •<  . 

•»  * •►  ■ V A - V 


' '•  ’v^"' 

-.  . V *1.  ,^-'  * 


K*>*‘‘ 


*./ -n1 


''"T  . 1 » • 

• **M  - meiti 


1“ 


•:  ..  J - 


82 


TABLE  6 

Classification  of  Coal 

Jigs 

Cha-racteristic 

Features 

Piston  Jigs 

Pan  Jigs 

Equa.1  pulsion  and 
suction  strokes. 

Luhrig 

Piescher 

Coppee 

Forrester 

Foust 

Shepard 

Leh i gh  ( an  thrac i t e ) 
Pittsburgh 
Elmore  600A 

Stewart 

America,n 

Shannon 

Simplex  (anthracite) 
Christ 

Suction  reduced  by 
differential  piston 
or  pan  motion. 

Elmore  500 
Elmore  600 
Elmore  800 
Humboldt 
As  terspey 

Pittsburg 

Suction  reduced  by 
valves. 

Hoyle 

Montgomery 

Elmore 

Pittsburgh 
( Shannon^ 

( Stewart^ 

Pulsion  only  pro- 
duced by  compressed 
air. 

Baum 

18.  Trougji  Washers.  The  old  hand  cleaned  trou^  washers 
which  were  so  widely  used  in  the  coal  fields  of  England  and  Scot- 
land up  to  about  1890  are  now  entirely  obsolete,  althou^  up  till 
very  recently  some  of  the  improved  traveling  riffle  type  were  still 
in  use  in  Scotland.  The  most  common  of  these  was  the  Elliot  washer 
in  which  riffles  were  carried  on  a traveling  endless  chain  which 


^Shannon  and  Stewart  jigs  are  made  both  with  and  without 
an  auxiliary  bottom,  containing  flat  valves,  below  the  screen. 


, m -.  AMt  uW 


83 

moves  the  riffles  slowly  up  the  inclined  trough  and  dumps  the  ref- 
use over  the  upper  end.  This  washer  is  similar  in  operation  to  an 
inclined  drag  conveyor-elevator.  The  Scaife  washer  manufactured  in 
Pittsburgh,  Pennsylvania,  was  a trou^  semicircular  in  cross-section 
through  which  the  coal  was  flushed  by  a stream  of  water  and  kept 
agitated  by  rocking  arms.  The  refuse  was  retained  behind  semi-cir- 
cular iron  riffles  and  was  discharged  by  dumping  the  hinged  bottom 
of  the  trough  at  intervals. 

A revivial  of  interest  in  the  trou^  washer  is  reported 
in  Belgitim  with  the  introduction  of  a new  modification  called  the 
Hheolaveur.  This  is  essentis-lly  a rising  current  classifier  attach- 
ed beneath  the  trough  and  communicating  with  the  refuse  slots  or  the 
pockets  behind  the  riffles  in  which  the  refuse  is  collected.  The 
Rheolaveur  is  an  inverted  pyramidal  cast  iron  box  which  fits  on  the 
bottom  of  the  trou^.  In  the  hopper  bottom  is  a spigot  for  drawing 
off  the  refuse  and  a water  inlet  pipe  to  produce  a rising  current 
in  the  slot  which  assists  in  assorting  the  particles  dropping  out 
of  the  coal  stream.  The  Rheolaveurs  are  placed  at  intervals  of  a- 
bout  .ten  feet  along  the  trou^  and  those  which  draw  middlings  are, 
in  some  cases,  discharged  into  another  trou^  for  rew^ashing.  At  the 
St.  Nicholas  pit  of  Societe  Des  Charbonnages  de  L*Esperance  et  Bonne 
Fortune  near  Liege,  Belgium,  Coppee  jigs  were  abandoned  because  of 
the  hi^^  loss  of  coal  in  the  refuse  and  Rheolaveur  trou^  washers 
have  been  installed.  The  advantages  claimed  are  cheaper  operation, 
no  moving  parts,  small  floor  space  and  head  room  required,  and  sim- 
plicity of  operation. 

Results  secured  at  the  St.  Nicholas  plant  referred  to 
above  are  reported  as  follows;- 


j.  r-jLO'iS  : \ i * xu‘ 


etiff  jovCai 


•...  l .C-no  erf^  '^'  vo  o«i/ 

I ill  o'<  r .'.t:j  •- I - -i?-'  :v.  - lox^vnoo  bvf.’ilt'rr; 

"•.L*  O ' ";J:  'r..^  loX:  u=»:;  >'0' .i  S , ‘ v,  jfi  , :.MU4/dlr  i ’ 

[■  'V.'  *r 'J  X.  *.  o-^:;  G 'C  boHo-'X'i  2'ir  X.go:)  .oiXvr 


- ' ‘ -Inp:i  Xfti. 

':*J  o©aii.‘ 

■*I  i5_  \'y 

■'airXm  9.*<  , x-  ' 

, ^^.o  o i ‘■)'»%  tX 

t.;l'  7’f3 

-■  ,■ 

.::  " nav?  jbiii7  aaXltX'i  sio'xl  iulcro 

' JSuJ’*:  oqo'i  etl 

■ ^a> 

•ir-k  x;v  ? 

' 'Xi  ©r 

r • v'srX  ;!  *jr  J .y 

lil  ;tan';  t lo  fr  Xv -v’^n.  A ’•  ' 

r>:  .4  '■•'  «1 1 

ax>.tJ  Gv/  ' ' '. 

• Iv  GviXo^bciJ” r X ofi;  X'v’  rt'i^Xotl 

7 •* . "C  X i.  *v 

F.  X-.. 

ry  ;>  1 J r- 

.0:  . xX-' f#Xrac'-.inc  g1  eiii"’  . -JovoI 

•£.:  '.' 

’ ‘ r*-'.  ■ ; ■J'  ^ 

•.it r=Gi.f./.GTuCO  i fi'U’C'tj’  5*:^  Xfa4B9i1l>cf  ^ 

• '■'-DO*.  )o  ni  iv'‘X  (j1  9.;^ ' Jbfrlrieo'  0 ; 

tt  ».,v 

0:fJ  :io  ibir^"  .10.^  *!o-.X  Jcflo  li,'' j r:  o- '■'‘ft 

•.i . ■.T-;  ...■'  i 'j  -j1  mc.^.)o;f  isqqorf  j.(j  r-J  . ■ o*r^  .vc.*-*- 

vH-.  - .Lr.l':  -I  *ju..  .'OT:’  s?  "4i'^  J0/..J  a iJ'tfl  .• -.  '.01  erij-ilo 

X»fG  ’,  J.q-0-ra  4 ; . iJ*roG4^  ft!  eJsi^-.la 

W ; 

-.  :»  nl  iv':''"  • i J . ;oo.jX<  «.•:  ."'firav 'i  oo.f-:  • , '■..-->1^00  *lo 

, ■-.'.•.'I*'  rivlilv  G-ac;<cf  ri;,yG'i4'  9r»^  pnui.-  . o'?  rioif.  X (v  ' 

O'ff  'c?':  ■'^jt/o'XJ  ‘Xyr'Joji/',  o.‘*  ax  ')9at.-'.  <*::ro;i 

..-  -.  »u; 

2:u'roX.  ^ roa'':/-  ^ .oc*:.tt:a.:r'''i;.TfO  c3l  ,)i:; uT’  lo  iiq  -oaloa'oiX  « t3 

; GG  j-.o  'f  jnxjfjii.  eT:>  -'  j;  oaoqoD  , -■Jijc ' --i  xl  onif  ^*xo'? 

"'ic'.ij  " r'  ijO'xJ  -rjifiv  •4x  0 .0  :p  o.i.'\  rx  QAi  ‘:1  I *700  lo  cvioX 

.aoi^  .'l-vqc  -t:.::-  Dx:a  )v-t:x.vry  ^4cni  n^o:i  ev<^  = 

- -•■*,■  , 'jd'iiapo't  noo*x  ' '.'Gj.qti  *icoX1  XIat‘  , ' jjniroa  o.-* 

•-"  , - ...ui..b,i:>';o  'to 

. . yj  -T'c  j;ulq  G.-^Xorb'  . Q.ii*  i'.xjoosr  a/'.:  /fGG': 

. -;  ^yX.r. -j/i. ' bs  i)  yi..  ^rotf-e 


84 

Per  cent 
Ash 


Raw  coa  1.  . . . 26.0 

Washed  coal  from  first  trough 7,3 

Washed  coal  from  second  trough 10,2 

Refuse  first  trough,  first  and  second  orifices 71,8 

Third  orifice 34,9 

Second  trou^,  first  orifice 68,8 


Third  orifice,  final  middling.  31,8 

19,  Concentrating  Tables.  Within  recent  years  reciprocat- 
ing tables  of  the  Wilfley  type  have  been  adapted  to  the  concentra- 
tion of  small  coal  and  installations  of  such  tables  have  been  made 
at  a few  American  washers.  The  V/ilfley  table  is  manufactured  by 
the  Mine  and  Smelter  Supply  Company  of  Denver,  The  machine  con- 
structed for  coal  w^ashing  is  called  the  Massco  table.  All  the  manu- 
facturers of  concentrating  tables  have  now  adapted  their  machines 
to  the  treatment  of  fine  coal  and  are  manufacturing  tables  especial- 
ly designed  for  coal  washing. 

Fig.  11  shows  the  small  size  Plato  coal  washing  table 
which  is  manufactured  by  the  Deister  Machine  Company  at  Fort  Wayne, 
Indiana,  The  underconstruction  of  this  table  is  shown  in  Fig,  12, 
The  commercial  size  table  is  fourteen  feet  long  by  six  feet  wide. 

Fig.  13  shows  a Deister  Overstrom  coal  washing  table  in  operation  at 
the  testing  plant  of  the  Deister  Concentrator  Company  in  Fort  Wayne,  | 
The  Butchart  table  and  the  Overstrom-Universal  table  have  also  been 
used,  at  least  experimentally,  for  the  purification  of  fine  coal  and 
•with  a fair  degree  of  success.  These  tables  are  all  very  much  alike 
in  principle, 

A concentrating  tabled  as  used  in  coal  washing  consists 
essentially  of  a linoleimi  covered  plane  surface,  or  deck,  approxi- 

^Coal  Washing,  Horatio  C«  Ray,  Coal  Industry,  Nov.,  1919, 


05 


The  Laboratory  Size  Plato  Coal  Washing  Table 


86 


12-  Underconstruction  of  tiie  Plato  Table 


^H.I, I>»  JWI , oa-'-g-ice  imjn.ow 'i»n  .-wotiHritHp! 


kl  • ’ 


88 


mately  the  shape  of  a parellelogram,  transversely  inclined,  and  re- 
ciprocated 230  to  270  times  a minute  hy  a head  motion  mechanism. 

This  deck  is  supported  by  means  of  toggles,  or  slides,  on  a tilting 
frame,  which  allows  the  transverse  inclination  to  be  readily  chang- 
ed* On  the  top  are  tacked  wooden  cleats,  or  riffles,  which  taper 
vertically  from  the  head  motion  end,  where  they  have  a thickness  of 
about  one-half  inch,  to  a feather  edge  at  the  '‘refuse  discharge  end”. 
The  riffles  are  about  one-fourth  inch  wide  set  about  one  and  one- 
fourth  inches  apart,  althou^  this  varies  somewhat  according  to  the 
material  treated. 

Their  operation  is  as  follows:  The  raw  coal,  previously 

mixed  with  about  twice  its  wei^^t  of  water,  is  delivered  to  the  feed 
box  in  the  upper  corner  at  the  head  motion  end  of  the  deck,  and 
thence  throu^  a series  of  small  holes  onto  the  deck.  Water  dis- 
tributing boards  are  provided  and  attached  to  the  same  side  of  the 
deck  as  the  feed  box  in  order  to  obtain  a nice  adjustment  in  the  I 
distribution  of  water  over  the  deck  surface.  A slight  side  inclina- 
tion at  ri^t  angles  to  the  line  of  reciprocation,  and  )idiich  is  ad- 
justable in  order  to  meet  changing  conditions,  permits  the  clean 
coal  to  be  washed  down  over  the  long  edge  of  the  table  into  a trough 
or  launder,  while  the  action  of  the  head  motion  in  reciprocating  the 
deck,  drives  the  sulphur  and  refuse,  which  stratify  next  to  the  sur- 
face of  the  table  deck  in  accordance  with  their  greater  specific 
gravity,  out  and  over  the  short  edge,  or  refuse  end  of  the  table, 
where  it  is  caught  in  launders  and  conveyed  to  the  refuse  dump.  The 
v^ooden  riffles  on  the  surface  of  the  deck  aid  in  the  collecting  and 
guiding  the  refuse  to  its  proper  point  of  discharge  from  the  table, 
and  also  prevent  the  finer  particles  from  washing  over  with  the 


fr- . ; ' 


r? 


'.0 ' I 

■ V" 


3v.’v;XIa  . 
-■  10^ 


- - , ' -.iu 

'■  -j  f • T ‘ ■ - 


i: 


J!>ii 


io; 

*w 

a 


•X  * 


: •-.‘•XO  nt 


■-  _J  i.  ^ X 


■t  J U "X  V - ' ■ ' : ; 

r . _i  . r , 

'>■-  ■>  '!.■-  ■:  1 ■ : j^Uti.l  : 

‘ ^ ^ " 'Is  . • 


;)  •:  • j 'V'  •’  ; ^ ^ ■ 

' -'  v'ii^  tt'r-;  L -''c  ■ 

- ' ■■;■;■■.  iC^V'  'C  r f;.-  * /I  j 


i.".  0'> 


•.'T 


i 

i ')  • c 


tj*  I ' »■>  4-  ♦ 

\ *•  * V J. 


- ')VX7  , ’V-sC  |T 

i, ^0  ; 

""  , 'iv.ij; 

:..i  i 


•’-  ■■  -J  •'•  .:i  biixs  i 


^n.'  1 • ■■  ’ • ■;  1 : *:i  . 


89 


clean  coal. 

The  coal  washing  tables  are  very  similar  to  the  ore  ta- 
bles. The  principal  changes  which  were  made  in  order  to  use  them 
for  coal  washing  being  in  the  riffling,  which  generally  is  deeper 
on  the  coal  washing  tables  although  so  many  kinds  of  riffles  have 
been  used  in  experimental  v;ork  v/ith  the  various  tables  that  a gen- 
eralization is  uncertain.  The  Deister-Overstrom  table  is  made 
larger  for  coal  washing,  being  seven  feet  wide  by  sixteen  feet  long, 
as  compared  with  six  feet  wide  by  fourteen  feet  long  for  the  ore 
table. 

The  first  use  of  concentrating  tables  on  a commercial 
scale  was  at  the  Stag  Canon  plant  of  the  Phelps  Dodge  Corporation 
at  Dawson,  Nev/  Mexico.  A Wilfley  sand  table  was  installed  there  in 
1906^  and  used  for  some  time  as  an  experim^ent,  but  was  abandoned  be- 
cause of  its  small  capacity.  In  1911  further  experimental  v/ork  was 
done  with  the  larger  Massco  table  and  an  installation  of  twenty- 
four  tables  was  made.  Since  that  time  practically  all  the  differ- 
ent tables  made  have  been  tried  there  including  the  Dutchart,  Plato, 
Deister-Overstrom  and  Overs trom-Universal.  In  1917  there  were  fif- 
teen tables  of  all  makes  in  operation  there,  mostly  Deister-Over- 
strom, as  this  table  was  preferred  there  at  that  time  because  of 
the  hi^  capacity  secured  by  the  large  diagonal  deck.  In  1919  an 
Overstrom-Universal  table  was  installed  for  experimental  purposes 
end  the  following  results  were  secured  in  a test  ruri2. 

•^Personal  communication  from  Mr.  J.  B.  Morrow,  formerly 
Supt.  Coke  Department,  Phelps  Dodge  Corporation,  Stag  Canon  Branch. 

^Coal  Washing  with  Concentrating  Tables,  J.  B.  Morrow, 

Coal  Age,  Sept.  25,  1919. 


liu  a-rc  ot  ii  i I.  . 

pvn  ^,*  o'.-!'j  c.'  ox  ®h -wi  rf'  j . ■ i it.R/1  o 1*5  -•  •-• 

•yo^oah  »i  ,-  'xX^liT  c*d:  oi  ?tuiO’J  : i lXax  v x-vo  . lot 


"v 


77Xi'  7u 

aX>ol:{  \r:'!.. 

;i  o'j 

rtqi'C' 

’J..a 

'.:  a--;x:- 

o‘/or'^..5  ^ 

#.^4  1*  «r* 

-i  .j 

noii s . 

vifiU 

V fT-  i3  5» 


I 


,;oX  jaa”!  oc  .•;.t:i.i{r>  ebtw  f oove  2 :,r:i  ‘.  j , ,'rii-iB  ^ • :.  vioo  i : * 't^BT 

^•to  ^•^■‘  lo't  jiool  M<’  rl-l  - -xkQ  I'J  ba'ij.ijroo  e ^ ;| 


r: 


I r- JO  ..:  no  3«Icr.-;x  'V  arfT'  j 

noiw  ist'iqt oD  o^uo  ,'  m .*  ’■  ) J".  j-i.f  -;j.< 

I ••►■  f X • ;.'  oi'Xo'^  -»  -<s  x^sTxi  iW  / . ^ ,co.  ir 

Cf  ^ 3 il  C'?"' , ' ' '■  • '*^3  i'-'  •■> ->  d'-tiJ*  <'>.‘-Ci-  *X-T  5S©.'  >iU 

,;-7  X -r^r^J-wi  JLJLvX  nl  . Xiwjfc-  XX^'jjb  aix  Xo  o'i  j 0 J 

-vJ-ia-rJ  1'  .'toix  wT.  f.  iXr.'.’.i  n-ri  i)o»  .»I.x.  .j  vjueAZ  a/'fX  f(X*  w,  o-  'ii7 

XX^  t a?  t ' sr.XX  . '-a;.t  ««w,  ^fuo'x  ■ 

' ^ 'Dtijd  oiJ  T ^X-^JfloiTi  b.‘ asod  ->vsrt  aft-is  a-«ld- * X.i»  jt 

' ■'•;  - I 

- ' vr^^r  nl  . r anov i mi ai^tvO  i-0f'S3 v.  - «iX > 

- • iiaon  :Toi".«5ta<[o  rJ  asy.^-:  IXs  *io  a©Xo -X  roa^ 

^ * * / 

7c  XrjiX  ^je  jioxrv?  hr>vio'lr'Tq  er^w  sld.ra  , /O’x^  p. 

■ .1 

ei‘:.i  I’i  , XBr;c'7...X  -.  •’;.*:  o ■ " v. x \;:tXo.7.q  'O  ffJLsl.i  f)-:J  ■ 

urc^cu'Xuq  noszX'iD^ix^  7 . XI..,?« ox  nX''\.X  Xiic^  i'aviol -::riJ'aTejvO 


r O 
VisA 


•;:/'.  *';s. 


rij  tlXXuy''T; 


r.’oXXo'l  '.iU  bOji 


v^Ltar^v  ,.VO'ii'X:> 

-.•j.r.  ono*.-'  »••--■ 
. '^  ■'■•  • * ^ 


.-”.00  7'-  nol-t  nointx;r."’C')  f7oor."ie^*, 
lioioq'XOO  -’-o-'T  aqZtii'  .iquB 

.i  --«rl  ..'ll ^ificrio:''  rfJitt'  XaoO^ 

.ex<ir  XsoO 

, ? % . • 


90 


The  feed  to  the  table,  which  consisted  of  reground  mid- 
dlings from  jigs  contained,  as  shown  by  a sink  and  float  separation 
at  1.40  specific  gravity; 

46  per  cent  of  material  at  48.0  per  cent  ash 

54  ««  M « » 11, 3 *•  » •• 

Total  feed  100  per  cent  at^^.  2 per  cent  ash 

The  products  from  the  table  were 

49,0  per  cent  of  clean  coal  at  11.6  per  cent  ash 
40.6  « « refuse  at  48.7  « « '» 

10.4  '•  " '•  middlings  at  27.5  ” » •* 

100,0  Average  27*66 

The  raw  coal  handled  at  this  washer  is  a very  difficult 
one  to  wash  as  it  consists  very  largely  of  boney  coal  and  thin  bands 
0 f shale  and  coal  interstratif ied,  Mr.  Morrow  reports  that  the 
Overstrom-Universal  table  gives  better  results  than  any  table  they 
have  used. 


Extensive  experiments  with  the  Butchart,  Deister-Overstrom, 
and  Plato  tables  have  also  been  made  at  the  Middlefork  washer  of  the 
United  States  Fuel  Company  near  Benton,  Illinois,  but  as  yet  no  per-  | 
raanent  installation  of  tables  has  been  made  there  although  it  has 
been  thoroughly  demonstrated  that  tables  will  reduce  the  sulfur  con- 
tent of  the  fine  coal  lower  than  will  the  feldspar  jigs. 

Other  plants  where  concentrating  tables  have  recently  been 
installed  are; 

Table  Used 

Renton  Coal  Co. , Renton,  Washington,  Deister-Overstrom 

Potter  Coal  & Coke  Co.,  Coral,  Pennsylvania,Plato 

Jamison  Coal  & Coke  Co, , Hannastown,  Pa.  , Plato 

Lackawana  Coal  & Coke  Co. , Wehrum,  Pa. , Deister-Overstrom 

Duncan  Coal  Co. , Greenville,  Ky. , Plato 

Carbon  Hill  Coal  Co.,  Carbonado,  Wash.,  Plato 

Carbon  Coal  & Clay  Co.,  Bayne,  Wash,,  Plato 

Madeira-Hill  Co.,  Several  Anthracite  break- 
ers  in  Pennsylvania  Deister-Overstrom 


* f 


> ■ 


.vtiilaMtt  »<  »•  * ■#] 

?i  :’fC'YA 


• •» 


:r 


;.'v:'w  o 

■'■-■  i^- 

■•:tc  •. 
Cl  ‘u?'- 


91 

The  chief  advantage  of  the  concentrating  table  as  a coal 
washer  lies  in  the  fact  that  the  operation  is  fully  visible  at  all 
times,  is  capable  of  very  close  adjustment  and  the  separation  of 
the  products  may  be  easily  made  at  any  point  or  as  many  points  as 
desired  by  simply  dividing  the  sheet  of  water  and  coal  coining  off 
around  the  discharging  edges  of  the  table, 

THE  CAl^EELL  WASHER 

The  Campbell  washer  is  a bumping  table  similar  to  the  Gil- 
pin County  bumping  table  developed  in  the  early  days  of  mining  in 
Colorado  for  the  concentration  of  gold  ores. 

Ten  of  these  tables  are  in  use  in  Illinois  at  the  No.  7 
mine  of  the  Big  Muddy  Coal  and  Iron  Company  at  Herrin.  Eig.  14  is 
a rough  sketch  showing  the  general  features  of  the  machines  used  at 
this  washery.  The  tables,  five  feet  long  by  two  and  one-half  feet 
wide,  are  made  of  one  inch  oak  plank  on  a 4”  x 8”  oak  keel  (a)  and 
is  supported  in  such  a way  that  it  can  reciprocate  longi tudinally. 
The  bumper  pulley  (b)  is  driven  at  one  hundred  revolutions  per  min- 
ute giving  the  table  a two  and  one-half  inch  stroke  with  a bump  on 
the  back  stroke.  When  the  cam  (c)  passes  the  keel  (a)  the  spring 
( d)  jerks  the  table  back  bumping  the  keel  against  the  pulley. 

The  table  is  inclined  slightly  toward  the  washed  coal 
launder.  The  coal,  flushed  onto  the  table,  as  shown, near  the  back 
or  refuse  discharge  end,  is  carried  forward  by  the  flow  of  water 
and  washed  over  the  end  of  the  table  into  the  washed  coal  launder. 
The  bed  of  coal,  as  it  travels  down  the  table,  is  agitated  by  the 
jerking  motion  and  the  heavy  refuse  collects  on  the  bottom  lodging 
behind  transverse  riffles  (e),  which  are  vertical  on  the  back  side 
and  slope  gently  on  the  front  side  (toward  the  washed  coal  discharge 


r<? 


/■  0- 
li: 


V 


' . f>rj:  'iv  i , jv.si  ,.  - ' 

■ vr::u-2  «.!.  „.-,xJr.Mgc  .rf; 

,0  nriJ  '.■  .-.-,2,;,V 

-.i-.,  ,.::  ; :'■■  T .-vtoq  Tf.  .■■>...  vXloee  »a  v rf.-atbo^q  9;.- 

•■••■“**  - '•'V;"‘-  i -.itivlb  v:£qal«  ,rf  b„x.  . 

■ *'*  :f;.«i6  j.xj 


,.  „'kV  .. 


lU 


» . 


STKT  ' 

■ X-  'ir  aK-'B  ,xiai  ].,.  iqnorf  , 8J  .;,..(te  ■ .:X;-v™«0  1/r 

r -i-b:  in  ,v."b  ■..:••  ■!  a.'.‘  ni  ^ -.qai., 9l,x;j  5^2,,  „j 

^ ncij Kuns.-noo  '*v»  cXjnolo^  '■ 

rfl  SJO.-.I  I jr."  nl,  !1'_J  cbXj‘:J  ■,'../x  jn  ..^.j. 

' xnaqaioO  'iinl  ti^cl  ^t-iniV  •jir  ,k_*  'tg  onim 

-ml,..  n,ij  iij  (,iix  Si/riwoiiB  dOJfljiQ  ffcucr;  it 

b.j.  o»j  ..  i-jot  n»t  ,v.  L.Xjji  srii  .vTSiXijis’.'olr;*  '! 

( •)  ■ ..  i.o  -X  "^  « no  )Ct;X,|  jso  n-.':  i »no  lo  si_.  ,oot.  # 

. X«r.Xb2,-llancX  3J  x.-xqio.-.,  m.o  •!  l„u  y.;,,  , ;ono  ni  bsXioqqxya  „x  ^ 
-i:-:  ...  ..oxi.xovo,  i,ei.nnr  .no  d..  ne  . u!  .•:XXno  ,oq<m;d  ,b,.T 

00  q,..-..x  n .x,x.  . .0.x;u..--:  „■  on.,d  . -nXvis  ..n 

-■•i.c..  •Jrf.  {,nl  r.„^  ojn.uq  (o)__,  ^o  Jdi  r”v  .o-jt<yt)a  s.ii'^j 

,,  .,oXXoq  ai..-  o;'J  b1<Jx:}  sa.  x, -.■*{,  (h)'- 

X-o-  ),xXsi*  i,nn  v,x  -xri.lsiXr  -„~xxr^nl  al  sXrfaJ  onT'  • ,■  g 


..  1 •l.:nr.,  .r„orfb 


loxav.-  -to-,,011  odi  ..;(  ,j.  sa-x^.^oolb 


.n  x,^,,.r  raoo  />»rtB«w  arfj  o;rJ  aXoaJ  a:-!  lo  iae  9 rj  loro  bad^t,  Ai 
,i.a  v.f  f>o,*,:JX5,a  .-'■dcj  o,;a  sXovinx ...  j^-.  •io'tod  w;V  f 


Eo.Mod  n.;j  no  oiDo'/oo.,  'c-.  odi  a,.,  api  Joa- ? . • 

'i.;  .ioi, .;  orfi?  rro  <■  ' =»  r“->i  - — 

‘ «'  ^ on’ioY£iu''T:i  i* 

‘.Il'ti:  p:>,..  ■=.  vXXn.s  :3qoXp 

.4“'  ..... 


The  Campbell  humping  Table  as  used  in  Illinois 


sT’. 


V- 


'**  *i^'^i.<*#Hffi . 'V'  ,'-‘^4 


-•  • ■ -T  • 

..w:  V.'^'^  ■■'■■.;■  '^■-- V 

< ■ . ''. '-till  .i  » ■ .,  V 'TW  ' 

^ ■ .4^  ■ : vV , v:-% 


■n-  c 


9i 


A 


'■  *'  1 *■  ^‘  ’ *3R  . "'  ' >'* jjHM 

. .,  ’ *'^  ^'--1  .•■<:  . . .1,  >••.  (■. ^ • 

, v_  , W** 


■ ..  A'';  ‘ . ,J 


"■A'fy 


40 


» .' 


iBr'VK  '’■  /■  >■  , ■ A'Tx  ■ ■ ' '' 

. ik  . t L‘  If-  • "^ 

fv  •_  1.  <A  NL  ?/  ✓ ■ » i/  -'.w^ 


, 


r ^ 

* 


t 


V 


♦<1>'  I 

av-'*  ’'’\ 


£. 


* ..A^,  * ' ■ ' •' 

•.'  / -7,  ■'‘**7,  w':’.  ..*^,  ■“  a »,’ 


^ . 


i'A-'  .’S  ■-,  *'"'■  ' 

S t‘4  A 7'  ' 


lit  V* 


,r  '.■' 


lir 


-I’:  ... 


; A:*'"  ••,■■' 

j,l‘  {‘-f 


/t*. 


V;t 


i * • r.  ' 

*'  !-7' 


. . , 7... 

•■V  .A'-  ' . ' * '-/.'  .S.^T 


5 K 


^C:'' 


-S. 

■•  .ir  :-4 
t»?' 


• ,,  '-A  !^-‘''v.v  ;:/^  .V.  ■'.*.v^ 

‘ji  ^’■  '-’■'■•'a 


* . . . 


3 


■\r  •■■*'"  i 


95 


end). 

The  bump  which  the  table  receives  on  the  return  stroke 
works  the  refuse  back  against  the  inclination  of  the  table  so  that 
it  is  eventually  discharged  over  the  back  end  of  the  table  into  a 
refuse  chute  between  the  piers  which  support  the  bumping  pulley. 

The  efficient  operation  of  this  washer  depends  upon  the 
adjustment  of  table  slope,  volume  of  water  used,  length  of  stroke 
and  tension  of  the  spring  to  such  a condition  that  the  heavy  refuse 
will  be  worked  toward  the  back  of  the  table  by  the  bump,  while  the 
lil^t  coal  will  be  carried  forward  by  the  flow  of  water. 

Campbell  tables  are  used  in  America  at  the  following 
plants^  for  washing  coking  coal: 

Cambria  Steel  Co.  Washery  No.  1,  Johnstown,  Pa. , 

Erected  1905 

Cambria  Steel  Co.  Washery  No.  2^,  Johnstown,  Pa*, 

Erected  1920 

Lackawana  Coal  & Coke  Co. , Wehrura,  P&. , 

Erected  1905 

Dominion  Iron  & Steel  Co. , Sydney,  N.  S. 

Erected  1905 

Cascade  Coal  & Coke  Co. , Tyler,  Pa. , 

Erected  1906 

Vinton  Colliery  Co. , Vintondale,  Pa, , 

Erected  1907 

Jefferson  & Clearfield  Coal  & Iron  Co. , Ernest, Pa. , * v. 

Erected  1908  100  tons  per  hour 

In  addition  to  these  plants  for  washing  coking  coal  a number  of 


^Personal  communication  W,  E.  Winn,  Heyl  & Patterson, 
Inc.  , Pittsburg,  Pennsylvania. 

^Now  under  construction. 


36-12  ft,  tables 
200  tons  per  hour 

36-12  ft.  tables 
200  tons  per  hour 

56-9  ft,  tables 
235  tons  per  hour 

48-9  ft.  tables 
200  tons  per  hour 

36-9  ft,  tables 
150  tons  per  hour 

24-9  ft.  tables 
100  tons  per  hour 


•J 


’ •i^-v  'lo  aciiT.  ^ 

u ' . ■ ' c:j  4 . 

t ' 


f 


V 


' .:-L 


> X 


washeries  for  preparing  coal  for  fuel  are  in  operation  in  America. 
This  table  is  also  used  in  Great  Britian  where  it  is  called  the 
Craig  washer. 

20,  Classifier  Washers.  Washers  of  this  type  have  a con- 
tinuous rising  current  of  water  vhich  is  strong  enou^  to  carry  the 
coal  particles  up  while  the  refuse  settles  against  it. 

The  Robinson  washer  consists  of  an  inverted  steel  cone  in- 
side of  which  are  vertical  arms  and  stirring  plates  revolved  by 
gears.  The  bottom  of  the  cone  opens  into  a cylindrical  refuse  cham- 
ber vhich  is  closed  above  and  below  by  slide  valves  operated  'by  steam 
pistons.  The  rising  current  of  water  enters  at  the  bottom  of  the 
cone  throu{^  perforations  in  the  top  of  an  anular  ring  which  sur- 
rounds the  refuse  chamber.  The  coal  to  be  v/ashed  is  introduced  at 
the  center  of  the  top  of  the  cone.  The  material  in  the  cone  is  kept 
in  a continual  state  of  agitation  by  the  stirring  arms  and  the  ris- 
ing water  current  carries  the  li^t  coal  over  the  top  of  the  cone, 
while  the  heavier  refuse  particles  settle  into  the  refuse  chamber, 
the  upper  slide  valve  being  kept  open  and  the  lower  valve  closed 
during  washing,  V/hen  the  refuse  chamber  is  about  full  it  is  emptied 
by  closing  the  upper  valve  momentarily  and  opening  the  lower  valve. 

A photograph  of  a model  Robinson  washer  in  the  Mining  Laboratory  of 
the  University  of  Illinois  is  shown  in  Pig,  15,  The  Robinson  wash- 


Fig.  15  - Model  Robinson  Washer, 


[ 


•rvr'strt'A  ::i  noii .'.’Xfic(o  tj  rr:v-  X-oo  ' *:  : ..itarioijw 

Oi.'i  h9ll90  ci  vi  O'l&ctr  rtX  *iv»tr  oci^  ■ d.Lrfi  j bH 

, •r'.'iuiiW  ^i«'. . 

. •-  ry:^'L  c :\^  9idS  to  . : . •>'>3^5?; 


I 


oaM  *^T:*r  :»  oJ  -^:  ;>".o  ^rrctJR  ni  tU>itt^  lo  ^noiTeo  nnjrcl**:  arOi;G^:J 


, ^ J i/r^.- .f.V' O'.:  co:ftt'T  fjX-i-stVf  ^:;  ,-. 'jX '.-4'T  X^o 

u.  wD  X^>o«o  £>*>J'?''v:  i as  Ic  w.''pia/too  rroonXi'oJt  e^n 

"li  '-.  ^vIcvj-  j .'Ti'' -iX^fE:  iii'L.-'  ax'xx  T^'V  a‘:];ji  /twIrJw  ‘it  t- 

*:>  • _ 

' £ ..oXr  v.ilvo  4.  o^ri  jaon  arf*  *.-*oi^u,‘  o ',■ 

.TSfjj-a  'i.  jo  c'-'X,:?  'c'  V’OlstX  Xii.-.  <.'gd>  cIj  oi  ;foXx^’ 

L:  1-’  -'oJ^od  oKX  i.':o..'‘c. '.  'leJ  c'-v  To  ^nc'in^ ' Sni  . i-j'-^orr:  ,aa.:;a'iq 

:j  ifoi/'.r  t;.X;r:  ii>;  'i<:^  :■  U ni  t.r'r/.t^eTC*lAt;  - jv': -ano- 

‘ ’'T.. o.  ’ cit*'  X nl  feo'^c  ; oX  c.*  Xaor-  oout**:;  o*'*'X  nbai.-o'*; 

. v.TDO  f»rCf  ni  X.-  X':eX.‘5iir  ‘'av  ►-aco  o '‘X  tr-  co^  0*1^  ir  o*iv4 

.:*r  .>  X Xj;r:  nnxviXX!,  vifj  v.  : r ? J ^ :roo  4 ai 

af’j  to  <TO.**“  ■4iJ‘  tv'vo  ■'  .00  eJ2  cLtri/io  *.tox-x/.*o.  toXiir  ' .tX 

03. •'  b"  c-.',i  oXX-'oc  i-i:L'to*r  i v-.o-'  © I:?  oil  . ' 

iJoao.Eo  0','X  •':  ' X i.di  'j:ia  ncqo  OvXiiv  il'iXc  v.iX 

cJi-.xX  Xlut  ..t'orfi:  si  'rni;t,.«i{n  ;i©u^  ♦’X.rirfiiX’i’:  ;:*!Xmt 

^ •.'/. .-V  ij^woX  : j?iri0i4O  b.i  1 'iXi'i-  X.  o:jo.i  or.ti^v  ©riX  :^nXooXt, 

v'l:  ■X.'. otiJ  ru  .tw  noeaitfof*  .■  "'O  ~i:  'r  oSct<q  A 


i 


■d:2^-r  ror.ni'Jofl 


,5. 


r >s 

fV  • 


ni  iTHcdn  fii  aicnxXXI  *1.^  • iiR^nvia^  &tf: 


L.  ' 


9 5 

ers  are  ten  and  one-half  feet  in  diameter  and  ten  and  one-half  feet 
hi^  with  a two  foot  discharge.^  The  Howe  cone  washer  is  similar 
but  shorter  in  proportion  to  its  diameter  and  has  horizontal  instead 
of  vertical  stirrers. 

The  Robinson  washers  were  very  widely  used  in  the  south 
at  one  time,  but  in  the  newer  \vasheries  have  been  largely  supersed- 
ed by  jigs.  The  following  new  installations  of  cone  washers  of  this 
type  are  reported,  however,  in  recent  years.  At  five  of  the  anthra- 
cite breakers  of  the  Lehigh.  Coal  and  Navigation  Company  cone  v^ashers 
similar  to  the  Howe  are  being  used  to  wash  No.  4 buckwheat  in  which 
the  ash  content  is  reduced  from  30  to  35  per  cent  to  17  or  18  per 
cent.  Previous  to  1916,  when  this  type  of  washer  was  introduced  for 
anthracite  preparation,  the  No.  1 buckwheat  was  the  smallest  size 
of  anthracite  washed.  It  is  also  reported  that  some  experimental 
work  is  being  done  with  the  Robinson  washer  at  the  Stag  Canon  wash- 
ery  of  the  Phelps  Dodge  Corporation. 

jijiother  rising  current  classifier  v/asher  which  is  attract- 
ing considerable  attention  in  Great  Britain  is  called  the  Drapers 
washer.  This  is  essentially  a tubular  classifier  with  a short  in- 
verted cone  in  the  upper  part  which  serves  to  constrict  the  diame- 
ter of  the  classifier  and  produce  a zone  of  maximum  lifting  effect 
v/hich  separates  the  heavier  particles  of  refuse  from  the  coal.  Re- 
sults of  experimental  work  carried  cut  at  the  first  plant  erected 
at  the  Glamorgan  Colliery  Llev/ellyn  are  as  follows; 

^Lincoln,  Coal  Washing  in  Illinois,  p.  25,  Eng.  Exp.  Sta* 

Bull.  69. 

^Coal  Washing,  Professor  George  Knox  Proc.  S.  Wales  Engi- 
neers, Vol,  34,  No.  3. 


013  '■>.  '.'-  I . 


. n" 
i:  o.t  . 


0 - J lo 


'M‘-  \;t^v 


-.  }■ 


' ' ■:•• : ■■  1 'o 

:yr^  n - R-i  $ , 

•jri  v,’0fT  ' iiiMolli" 


, :t»o 

•fc’.iV 


’vn^.o 


o ' -'.y',  • 


o'J  Ldn.l  ..  s 

, . ;i  t>'...  " •>  -.J  Uv  'C  ■■.'■ 

• ■'  3C:j<  : • J w nr.  ; 

, . ..  - WV  . X ■ - , , 

^ I • * ^ •*“  'V  '■  ■ • 


■ o '! 


: • ^ ■ ■ • 


^^t;o 


--  -V..'  ...  .. 

■3;..:.  ' 'j  'tc- 

. J:  : ’3;o;’Jar!' 

. .'• .;  010' 


c.  fJ 


o.,  . . • ,'j> 'C; 


V’  r ■ . I 

I X J-  •>.  ,4^  ■ ^ 

•■  .*.0:  'i.. 


.-f' 


■ . '1m  •vfC’  i . 

. . •*  !■  • IJ  W 

• 1,.  n 

;■;.■  .Jj  i.  OtlMijL*  . 


l.-.kj 


TT*;.  jc 


Results  of 

Tests  on  the 

Draper  Washer 

Material 

washed 

% Ash  in 
raw  coal 

% Ash  in 
v/ashed  coal 

% Ash  in 
refuse 

Fine  coal 

31.0 

5,7 

71.2 

H (1 

22.7 

4.1 

73.2 

Slurry  l/S” 

to  0 size 

23,7 

2.2 

70.6 

« 1/8 « 

««  0 '* 

13.8 

4,25 

67.4 

» l/8» 

« 0 ” 

30.2 

4,8 

71.7 

Samples  of  fine  coal  from  a Southern  Illinois  mine  were 
sent  to  England  in  the  summer  of  1919  for  tests  with  this  washer# 

The  results  secured  v/ere  no  hetter  than  have  "been  secured  "by  jigging 
samples  of  the  same  coal# 

21*  Cleaning  Coal  by  Oil  Flotation#  In  the  past  few  years 
some  experimental  v/'ork  has  been  done  with  a view  to  the  utilization 
of  the  flotation  process  for  cleaning  fine  coal#  This  process  as 
used  for  concentrating  sulfide  ores  consists  in  agitating  the  finely 
crushed  ore  with  water  and  a small  percentage  of  oil,  sometimes  also 
with  a small  percentage  of  acid  and  accompanied  by  aeration#  A 
froth, which  floats  the  ore  particles,  forms  on  the  surface  and  is 
skimmed  off,  Wcien  applied  to  coal  the  refuse  particles  sink  and  the 
coal  is  taken  up  by  the  froth#  Bacon  and  Hamor^  report  the  results 
of  tests  on  coal  washery  refuse  conducted  by  Dr.  C#  B.  Carter  at 
Mellon  Institute,  Pittsburg,  Pennsylvania,  Although  successful  in 
making  a separation  they  conclude  that  this  is  net  an  economically 
feasible  process  at  present,  but  ”it  will  undoubtedli'’  play  a leading 

^Problems  in  the  utilization  of  fuels,  Journal  of  the 
Society  of  Chem.ical  Industry,  June  30,  1919, 


N 


L 


1 


J . . 


■‘i 


\ 


! ^ n 


r 


. 


4 • 


u ^1.'  - . r (, 

I 

• . '.^r  oltfi 


97 


role  in  meeting  prominent  fuel  problems  of  the  future”.  They  suc- 
ceeded in  recovering  70  to  90  per  cent  of  the  combustible  material 
in  the  feed  as  a fuel  of  20  to  25  per  cent  ash.  They  report  that 
pyrite  floats  readily  with  the  coal  but  that  it  could  probably  be 
controlled  by  preferential  flotation. 

Tests  on  raw  coal  have  been  carried  out  at  the  Seattle 
Station  of  the  Bureau  of  Mines  with  similar  results.  The  Minerals 
Separation  Company  of  London,  however,  has  introduced  this  process 
of  coal  washing  on  a commercial  scale,  and  according  to  their  re- 
ports wide  plans  are  being  made  for  its  adoption  both  in  Britain  and 
in  Continental  Europe.  At  the  annual  December  meeting  of  Minerals 
Separation  Ltd.  Mr.  Francis  L.  Gibbs,  chairman,  outlined  the  plans 
for  flotation  plants  as  follows.^  Waste  heaps  and  current  v/aste 
from  washer ies  seem  to  be  receiving  the  most  attention.  A pilot 
plant  on  a commercial  scale  has  been  erected  at  Aberman  for  experi- 
mental work  on  this  material.  Three  commercial  plants  for  treating 
such  waste  are  in  course  of  construction  and  various  other  accumu- 
lations are  being  examined.  A plant  for  washing  coking  coal  has 
been  contracted  for  by  the  Skinningrove  Iron  Y/orks  Company.  A one 
hundred  ton  pilot  plant  is  under  construction  at  one  of  the  Collier- 
ies in  Prance,  and  plans  are  being  made  for  plants  in  Spain,  China, 
Brazil,  South  Africa,  India  and  Japan. 

'/i' 

^The  Flotation  Process,  Colliery  Guardian,  Dec.  3,  1920. 


/ 


98 

CHAPTER  VI 

ItETHODS  USED  IN  THE  EXAMINATION  OF  WASHERS 

22*  Standard  Methods.  In  ordinary  practice  the  methods 
used  to  determine  the  character  of  work  being  done  by  a coal  washer, 
consist  of,  first,  the  sampling  and  chemical  analysis  of  the  raw 
coal  and  the  washer  products;  second,  screening  tests  with  analysis 
of  the  various  sizes;  and,  third,  sink  and  float  tests  on  samples 
of  the  raw  coal,  washed  coal  and  refuse. 

CHEMICAL  ANALYSIS 

Analysis  of  the  raw  coal  and  the  washed  coal  for  ash  and 
sulfur  content  shows  the  extent  to  which  the  impurities  are  being 
removed  from  the  coal  by  washing.  Where  the  proportions  of  washed 
coal  and  refuse  cannot  be  determined  by  actual  weights,  the  yield 
of  washed  coal  secured  and  the  percentage  of  the  original  raw  coal 
rejected  as  refuse  are  sometimes  calculated  from  the  figures  for 
ash  content  or  for  sulfur  content  in  these  products  by  solving  the 
following  equations: 

Refuse  ash  - Raw  coal  ash 


Per  cent  yield  of  washed  coal  = 100  x 


Refuse  ash  - Washed  coal  a^; 


Per  cent  refuse  =r  100  x 


Raw  coal  ash  - Washed  coal  ash 
Refuse  ash  - Washed  coal  ash 


These  formulae  are  given  by  various  writers^  on  coal  washing. 


^Standardization  in  Coal  Washing  Reports,  Delama ter  M.  & 
M. , March  1912. 

^Coal  Washing,  Wendell,  Technograph,  April  1915. 


99 


SCREENING  TESTS 

Screening  tests  on  the  ravr  coal,  washed  coal  and  refuse 
with  chemical  analysis  of  the  screened  sizes  show  what  size  of  par- 
ticles are  being  cleaned  most  effectively  and  what  sizes,  if  any, 
are  not  being  cleaned.  One  application  of  screening  tests  in  loca- 
ting the  source  of  trouble  in  an  operation  v/here  satisfactory  re- 
sults are  not  being  secured  is  shown  in  the  following  table,  giving 
results  on  a coal  which  v;as  washed  by  jigging  at  0“  - I”  size. 


TABLE  8 

Screening  Tests  on  Raw  and  Washed  Coal 


Size 

Raw  coal 
*fo  ash 

Washed  coal 
*fo  ash 

% Reduction 

1«  - 

12.3 

6.8 

45 

12.  0 

6.  4 

47 

- l/8« 

14.6 

7.7 

47 

1/8”  - 20  M 

18.3 

11.0 

39 

- 20  Mesh 

22.0 

20.2 

8 

These  figures  show  poor  v/ork  on  the  fine  material  below 
l/8  inch  in  size,  and  practically  no  reduction  in  ash  in  the  sluge 

; 

through  a 20  mesh  screen.  It  would  probably  be  advantageous  in 
this  case  to  screen  the  raw  coal  into  two  sizes  - 1”  and  0 - -i” 
and  ^vash  each  size  separately,  or  to  screen  the  washed  coal  and  re- 
wash  the  material  which  passes  through  a ^ inch  screen. 

SINK  ANB  FLOAT  TESTS 

Sink  and  float  tests  on  the  washer  products  a.re  ordinarily 
made  in  order  to  detemine  the  amount  of  float  material  or  coal  be- 
ing discharged  v;ith  the  refuse  and  the  proportion  of  refuse  retained 
in  the  washed  coal.  In  as  much  as  the  separation  of  coal  from  ref- 


n*:  ' 


(I 


i V' 


L 


■ ^ i : 


L • • i ■>  ' 

9::  in  ' • 

, . - • j 


■J  V' 


O'*"*  'r  ;•.....• 

. -1 5.*  * a si  n Yi  :.  XaC  i :•-. . . «;  .♦ 

'■■'  -'■•••  oorr.oi)!-  j.-.i:,./  -:yi^  «ox 


^1,1' 


,z  •o’f.tnt*  j o-r -'V  r.i'i  * -.-.t  v.; 


» ..  " r - 


.J.  't 


vnJ 

_ M r * 


J I 


j -*  .'u 

V'-f  h'' 


fJOOL'  .‘on  DTK  »{-  '-f' 

X.KOO  .a  n:  olMij.’.n 


. .K-). 


- .IJl'CAV  _ 
i?--)  f ,-r  ‘ : J “ t : :-  i ; ; ■' 


X»QO  ' 


L»snr)  rsi^  * 
aca  > 


" ■'-  • ■ r.t.-  ' "■(,; 

-.  ■ .'■'■x  J c, 


•f- '■  ‘-1  ■(  rri  ri-.^i 


;Jt:!!V^':'  c'  vx.  ..-•;  .)-i-  ' n-xr 


0». 


/41 


A i -«  • 


• > i Ly'  ’ 1-’  C* 


-C-:.'0  r'_.; 


--  tit  . -■‘0  . 
' •:  X i 


w 

■ l'  >.. 

i)/' 

■ * ,i 

vX  •■•-  , 

. : '.''xi . 'r  C- 

-«-»•  » 

' ‘ 1'^ 

. . C-'i  < 

■;/.oar:  -zv 

‘ >M  f ■ 

' J-  0 

'^o'i ,; 

•T  .>a‘G  . ■ 

'» ••/  G 

1 

- ^ 

- . - V W 

OX"'. 

gg;jo:.:g 

iX  G.;i 

r?'^  1 i '£ 

,5,  • O': 

• '.■*  ,G  ; 

. Ow  aX  L ';il 

/ / 

C;kj  C’-Ig  0 .iT.tS  ^ 

\ t I .t  ,„i 


G'  '/.  n . ^ ) 


J.  ? - •.♦  - w .idiii. 


100 


use  by  washing  depends  entirelj”  upon  their  difference  in  specific 
gravity,  the  sink  and  float  test  is  the  ideal  method  of  checking  the 
work  of  the  washery.  Such  a test  when  very  carefully  made  gives  a 
practically  complete  separation  at  the  specific  gravity  of  the  solu- 
tion used;  and  comparison  of  these  results  v/ith  the  results  secured 
by  washing  gives  a measure  of  the  effectiveness  of  the  washing  oper- 
ation. Having  determined  by  a specific  gravity  analysis,  as  de- 
scribed and  illustrated  in  the  chapter  on  ‘♦Principles  of  Coal  Wash- 
ing”, the  specific  gravity  of  the  solution  which  makes  the  ri^t 
separation  to  produce  the  maximum  yield  of  washed  coal  of  the  re- 
quired degree  of  purity;  solution  of  that  specific  gravity  is  then 
used  to  determine  the  proportion  of  sink  left  in  the  washed  coal 
and  the  amount  of  float  coal  left  in  the  refuse. 

A machine  which  is  now  widely  used  for  making  these  tests 
was  developed  by  Mr.  G,  R.  Delamater^  while  operating  the  U.  S.  G.  S. 
fuel  testing  plant  at  Denver,  Colorado.  This  machine , caviled  the 
De lama ter  Standard  Sink  and  Float  Machine,  is  illustrated  in  the 
photograph.  Fig.  16,  It  consists  essentially  of  a rectangular  cast 
iron  tank  with  rounded  ends.  A strap  iron  frame,  which  may  be  rais- 
ed or  lowered  in  this  tank  by  means  of  a rack  and  pinion  device, 
holds  two  ten  inch  brass  testing  sieves  side  by  side  in  a horizontal 
position.  A ten  inch  open  cylinder,  which  will  fit  inside  the  test- 
ing sieves,  is  supported  on  a track  in  the  upper  part  of  the  tank 
so  that  the  cylinder  can  be  slid  along  from  one  end  of  the  tank  to 
another  just  clearing  the  sieves  when  they  are  in  the  lowest  posi- 
tion at  the  bottom  of  the  tank. 


%ines  and  Minerals,  August,  1909. 


101 


i?’ig,  l6-  The  Delamater  Standard  Sink 
and  kloat  Machine 


102 


To  make  a sink  and  float  test  the  tank  is  filled  with  a 
solution  of  the  desired  specific  gravity  and  the  sieve  frame  carry- 
ing the  sieves  is  clamped  in  an  intermediate  position  so  that  the 
cylinder  rests  in  one  of  them  forming  a continuous  cylindrical  ves- 
sel with  a screen  bottom.  The  sample  to  be  tested  is  placed  in  this 
vessel  and  agitated  to  thoroughly  wet  all  the  particles  and  disen- 
gage them  from  each  other.  It  is  then  allowed  to  stand  quiet  for  a 
time  to  allow  the  heavy  particles  to  sink  into  the  sieve  and  the 
float  particles  to  collect  on  top  of  the  solution  in  the  cylinder. 
The^.  sieves  are  then  lowered  to  the  bottom  of  the  tank;  the  cylinder 
with  the  float  particles  which  are  in  it  is  carefully  moved  over  to 
a position  above  the  empty  sieve  and  the  sieve  frame  is  raised  to 
the  surface,  bringing  the  sink  in  one  sieve  and  the  float  in  the 
other.  The  two  products  are  rinsed  thoroughly  with  water  to  remove 
the  salt  which  was  used  in  the  solution  then  dried,  weighed  and  sam- 
pled. In  this  study  the  Delama ter  machine  was  used  for  making  tests 
on  coarse  coal  of  jigging  size. 

In  working  ivith  small  coal,  such  as  some  washeries  are 
now  handling,  through  a -i-”  screen,  or  through  a 1/8”  screen  with  a 
large  proportion  of  slime,  a need  has  arisen  for  an  apparatus  in 
which  all  the  solution  used, as  well  as  the  coal  sample, is  divided 
into  a float  portion  and  a sink  portion  and  each  screened  or  filter- 
ed with  the  respective  float  and  sink  portions  of  the  coal  sample. 

The  machine  illustrated  in  Fig.  17  was  designed  for  this 
purpose.  The  apparatus  assembled  ready  for  use  is  shown  in  Fig.  17. 
The  three  separate  pieces  which  make  up  the  apparatus  are  shown  in 
Fig.  18  and  details  of  construction  of  the  barrel  are  shown  in  Fig. 
19.  The  machine  was  made  in  the  laboratory  shop,  of  a three  inch 


: -n  o;  o'i 

lo  ari^uXo?: 

T'  ijj"!.  !ii  r.X  ai  ;or  i:i  s**,  ^nJ 

LfTirTic-  V ■'■’.•  In  one  p?'o 
f Oi  ’Ol?;  . ,...>,■  J.C  f nc^O'IDri  i iJ’ir 

i.i  , . - .-  ,;I ir-L'p*r;'2r oJ  i^,;;  i)fi nsa:; 
o:*  r!oj^ 

-•  bn  c;i;  o;?f:i  ' ;ir  -.j  L:  :^;:*cd 

.-'■■‘-il-  ’ ;to.U^;-.  ,)r,  -.*j>  :»p-  qo-*  .0  *5dXIoo  9/^ 

:>.'jr.{.I v-^  . ; .'  . 

.*/  t i«v;.  *4.. . 


' ■ n i .,0.;  ; 

~ :^'\ . n 

ov:  Ic  9.-:. 

iw'  oil  ntjlXX^o.; 

- WT  i /■ 

-DX-n:  -i . -tj  cooorni 

*;i 

- ■ ■ I : i 

ini  «•-' 

ff»«e  'ii.'ii  -sicrt^ 

V o-  -^oifivoi  ®ir 


®’:r 


• .Iv -iNr 

0-''i  OJ  ?'-<■'!  ■J’  f.  •.  ; 

' .%■ 

'1  ’ll  >vfi;  C'>.;V/  -.'r  ?norj  .'^U" 

‘J  i *x”.  0 / ^ ri  nri*  ‘ 


'1  - 


OVQO,*  '■  • ■ j>j^*  M"iriC0  . >1 

• i ^ f?.  ' I*' ~f  , ^ jj*5 '■' **3  u'f’*'- 

X. ■'-  /!•■'::). fj  !;■  •■  .t ' 


^ n L' 


iJ  0 


)1  : .arff 


>y' LiniUti.:.'  on- 01; 


i V ■ 1 0'\  i ! n 


■J-*-  - 0 “*  - -‘'bOTi^  V 

V,  O3i:-io”-  ;.rlcT.:Ior  f.;,‘  ni 

<-  'i.  -in. ' I O'i  h*'riij  ‘ j j 

.-.  .<..1.  .1  . ^ .,;i.J  n.i  , . -.;j 

• >.^ln  ii.^.  oli.  i'*)  Xiicj  n;'rr>,i'i  .... 

‘ ’ . " - ■ ■•’  X J- .« '•?  . l:>  .t r : - i -.’'x 0^7  « 1 

■ i;.  0'i;':t  • , ■^rio-'  ’' 

• . 'N  •'  • *■'7  ■ ' ' 'I  > ’ -I  ..  . > ^ ^ 

* ■ • - - ^ ...  .i  jc  .:Ci  M 'X  ':  OT'J  ' 

M,:  , X . 00  ,:  •*  - •'  -r  ■, 

■ ''  1-...  :.;  .ioi  f 

J . i VO  i-f:,'”:^  ...  not.-i-X'^  X.:i-3  ..  , noi.i* 

. '.niiv:  X .;_D  ■>  V*  ; , d'uiO'iOc?  :(niB  5fi.n  X ;• 

. r'J  -xo'i  i,c.-ih>  ■'  .i.  -.  ni  .11:  o-i*  .-  0x7  • 

'^.  ■'.*■  » •'  *'  - V-'- :'•'£  X(  '“O'-iii  iflo+’.n-ijiQi.Yje  ft".'*;  , 'X-t.'*: 

'•  ■■  ‘ *^  :':  ■ X q:i  :.-  - yx.nl  -o.; 

ii  .c  '-:  ''l:n  a~  lJDin*iuico  X 

' ■'*  ' VI  ».■  X f:i  j ....  C5ii%'  ©.iX-noo 


.1.1  . . wer' 


.ioi  {‘‘o' 
oX  *l  ex . *' 

f: 


' •'  i ’>  Z Z\‘l  '.*'■■  ■ '' 

o .;’•  .'  : .,  oil '.  'll  , . i' 

1 , v> 

M 7m  i 


103 


« 


104 


u 


L 


1^. 


¥ 


V 


!••'  ■.* 

rA 


•% 


J 


•*  k 


V 


105 


ricj.H— D^toih  of  Darm.1  of  f/ew 
^inK  and  n oof  Machine 


roundway  stopcock  valve,  a piece  of  four  inch  galvanized  pipe  and 
tilting  frame.  It  is  so  simple  in  construction  and  operation  that 
very  little  description  is  necessary. 

The  bore  of  the  valve  plug  was  cut  out  to  four  inch  size 
at  one  end  a.nd  almost  through  to  the  other  side  of  the  plug.  This 
small  end  of  the  bore  v/as  then  filled  with  babbit  so  that  the  valve 
plug  instead  of  a three  inch  round  hole  through  it  has  a four  inch 
cylindrical  well  in  it  as  shown  in  Fig.  19,  In  the  valve  body  one 
opening  was  cut  out  to  four  inches  in  diameter  and  a galvanized  pipe 
ten  inches  long  and  four  inches  in  inside  diameter  was  soldered  on. 
The  opposite  opening  was  closed  with  babbit.  The  four  inch  galva- 
nized pipe  and  the  four  inch  well  in  the  valve  plug  form  the  con- 
tainer for  the  sink  and  float  bath.  For  convenience  in  manipulaition 
this  barrel  was  pivoted  on  a tilting  frame  fitted  with  a catch  at 
the  bottom  for  holding  the  barrel  rigid  i«hen  in  the  vertical  posi- 
tion and  a stop  for  the  valve  handle  to  facilitate  lining  up  the 
well  in  the  valve  plug  with  the  bore  of  the  galvanized  pipe. 

In  making  a sink  and  float  test  the  valve  handle  is  turned 
over  against  the  stop  forming  a continuous  cylinder  of  the  pipe  and 
valve  which  is  filled  to  within  about  two  inches  of  the  top  with  a 
solution  of  the  desired  specific  gravity.  The  coal  sample  is  then 
immersed  in  the  solution  and  stirred  till  thoroughly  wetted.  It  is 
then  allowed  to  stand  undisturbed  for  a short  time  to  permit  the 
heavy  particles  to  sink  to  the  bottom  and  the  light  particles  to 
rise  to  the  top.  The  valve  handle  is  then  turned  through  180  de- 
grees, care  being  used  to  avoid  jerking  or  jarring  the  machine. 

This  separates  the  heavy  particles  in  the  well  of  the  valve  plug 
from  the  light  particles  floating  in  the  upper  part  of  the  galva- 


■=; 


' K6.’'i  't:'o>  ' :->ofti-  , ■*  Xoo’. *.’;  ■f^^ 

iioiv  c'l'qo  ; : , - f.  ‘ '^.cr  nx  . oT^rcjia  oft  .*  ; , ml  * 


aoG* 


r- 


, -pf'Ofjr  ::  :''•  /♦ ^l^*t  X1£»V 

;i  't  './*■  c.'  - ;f'.'  .‘i  ■ ■■  ' -rC.'.y  of''* 

-''X'-io  ■'ro((^o  t .b  i.oirlj  -ucoiilA  iin,:  i»ns  b" 

: ■ ■'j  r-i  SIJJ3:S  dstv  b3'SS.:  t •.--*  orj  . ba^  /I 

; c ••  ■ V- i .1;  /iC’iff-  ■’’.Off  iMijjort  .Iv.ii  o©'‘»:.i.?  .«5  '. j b.t. oJtai  '7  ^ 

^a-..  i(]  ♦ ' r :•-  ".r-.'-'t  * :.  r.I  Xlct; 

, •/r*;'':  ;.  •.'•.'ii'’  ; j O ^TftX  oi  ' Jl/O  1 f . a ■;!  i.  • j 

VC!  ■;  xvj  <*  ,;.3l  ;■ 


'-  ai  ' a^-fanl  "WOl  ‘^s:  c,  .-.:  »r»I<©/il 

LUOl  a . - (■  ■"}.  Jb--  I-<  c V ‘ •«  i 


^ ' 


vlor'  .va 


Ju';  OTiJ  , ";nai  : ©qx  q o 


. 4i'  ■■  vt  c.r\  Liw  'xol 

iii  * ^ ■ 


1 

< . 


- >•>  rj;fJ  a*' J ar  fl.i 

'alJ-.Xa V i..;  Hi  *tv-- ? ..«,7.;Cr^  -v 

!.o.''.:j  riJi  - --'j.*/  •>..:***£'-  . ifi.  rj. Ji  bf>J.'vlcr  KMif  ex.' 

j..a.'J':.'  a'.'  ..i  .'5ic:.'  i‘- Xoi';;  ■'  or' ' . I >1  ;in  TO't  ■*  . 

: :.,v  7;.,*  :-.j  i 1 "si  lin/ifi  B’r  ■ y ’;d  .{O:!  -k  rl9  noi-:  ^ 

, ■ 'b-'-.;  " o-'J  c ,qoo'  u*«^  .'  v,  JL  • '/-'Iq  a*  / ;.  J ;:i  .La  - 

r:7;:.. 

J‘  O’  vJ  2-')  >.rj  Offj  Jac  . J i v oj  rl  c i.'.' 


> y r ’ li 


.w  siv  4©X'i  1'  ‘ty.tct  T ! 


^ !'■'■  r I o'‘.f^n*.  > laon  oitAV  J-yj  ii.OTi»i  . ‘ '.I?  1 ,’.:.x.v 


• .-  » w 


1 1 i «:  0.  ■ .t 0 1 * V/  r.  o€  f> 


r 


03X  a- 


: j h«in 


* V*  c • v/  .■  ■ i X 

.' i.  '•■■:)  ' >. . V.:.’  ' X'icv^'-  *:o':  b I'XJS^n.'?  ■■>  : .^  ; 

XI  f):!J  c . •:  v>.  X ui.^-  *?(rtXr!  oJ  ,,:<0 

■i:  ■ ‘ b ‘.vit: L' * rio  ■ Li  ovii  .’.v  L>vtT  ^ pii^' 

■ iq  jjaiil'io;,  Mov...  03  bm.u  .'>i- 


i 

rl  iv  ^ 


*’ : ,ic  :f 


ic  IC9<*  It  : a*  r»9X:jid?*i  j’i  \Vi- Qi. 


, ,vj  : ii.;;oX  ■ 'J.  oi ., 'r^^a  irlhiX 


107 


nized  cylinder. 

By  tilting  the  "barrel  of  the  machine  the  float  coal  and 
solution  is  then  poured  out  into  a fine  screen  or  a filter,  the  so- 
lution is  drained  off  for  use  in  another  determination  and  the  ad- 
hering particles  of  float  coal  in  the  machine  are  flushed  out  on 
the  filter  with  a small  stream  of  water.  The  valve  is  then  turned 
back  to  the  open  position  and  the  sink  coal  and  solution  is  poured 
onto  another  screen  or  filter  in  the  seme  manner.  The  products  are 
then  washed  v/ith  water  on  the  screens  or  filters  to  remove  all  trace 
of  the  solution  used.  By  using  this  apparatus  v/ith  filters  for 
washing  the  products  all  the  sample  is  recovered  and  there  is  no 
loss  of  fines  by  suspension  in  the  solution.  The  small  volume  of 
solution  used  makes  the  operation  with  a vacu\Jim  filter  fairly  short. 
On  samples  from  which  the  slime  has  been  removed  a ICO  mesh  screen 
is  used  instead  of  the  filter.  This  machine  was  designed  to  make 
the  separation  just  above  the  top  of  the  sink  in  tlie  cylinder  so 
that  practically  all  of  the  solution  carrying  particles  in  suspen- 
sion goes  v/ith  the  float.  The  float,  therefore,  includes  particles 
of  the  same  density  as  the  solution  and  lighter. 

In  the  literature  on  the  subject  of  coal  washing  the 
statement  is  often  found  that  the  sink  and  float  test  gives  a 100 
per  cent  perfect  separation.  This  means  on  the  basis  of  the  specif- 
ic gravities  of  the  particles  in  the  sample  as  they  are  at  the  in- 
stand when  the  separation  is  made  betv/een  sink  and  float  in  the  so- 
lution, A number  of  tests  in  which  the  float  coal  from  five  pound 
samples  was  retested  immediately  after  the  first  separation  showed 
from  one  to  three  sink  particles  in  the  float.  The  coal  tested  was 
an  Illinois  coal  at  size  in  which  the  average  proportion  of 


\-*0^ 


u . 


"...u  .r  rx  ft:!j  onirn.  I 


or'  :*: 


i.vo  brr.llS^ 

’ loitai  firiS  r\n’i.‘LiJ 

, . to  n?c:  '•*  " s.'X  ■ g^i  4; oi. J’ j'Xo'- 

'■'  ■-  ■ ■ t £j:i:l’ : r’i  8»jj  .'lo'l  ’I'ia  •i'Jt:’'  ui  l.’ ' 

I 

: r-o  ' 'r*Ka-/  o.ii/'j.V'f  r:i  laoo  ^ -ol’i  -jiJtaci  ; 

.'  v;  '?r.C-'V  £1  . t-ov’  lo  ' fl  ■ 

.i.-.  X.703  r>o’*  o;t  .-  ' X aocf  aeqo  or*  ex?  ■!;, 


D.'* 


■(  .!  .1  1 . ■'  /too  ioc  t'‘  ^*orr^  rrj  ■;  j 


-,c*I.i;'t  *i  / riir^.tf  .j  :• -J”  r.o  ner.X  J 


I 


;iv'  rrjrx  'O.;.!  ■(  . i,)t/  . - 'cic.is  1.03  ‘'  .'  'I 

■ ; .-o.)*-:  ;»1.  ' ‘ ".  > ' .'"’j  r U ’ 

'■•  ^"'l  * ’ ' t'i  * ifl  :'.Ox  rrt  » rs'.',  0 "I  r : n r:  r T ^1* 


t •:*:vo  "/  . ■ n*.  W.J  i'*r  '*0  *»iIJ  atfF'U-  noi''. .'. 


'>  ^4*  \ 


•-;  S:iO"  C '.:  i I'q-vu:*)':-  r' - , ,3-:'  ' .I'-!  -V5;t  ;:v^’iv 


1 ir.  a/.'  noi'  or.;-  r,j  . 

0:3  too  ■ ■'  • j •>  -»  r-.j*  , i 3 -!.  ■* 


C*  jt  ■“  v'  lO  o o * • ;-  pj.  1} 


. . ■/  * ucri, 


' , 


- ..:  r.i  30:3l"--r>i  1.  ''CiJ  ;00^-00r  'IC  Vt 

j >.  ; .r'^  ,.  0X“  or.  0 'J  :iox3- *g7 

»'  ' '■,-'  *’0  .'.\tJfIon  "..' / 0.  •.ejjf  orce  j.v*  'I  o 

} .').,vfO  r 

r Oj:  w"  •tTftC  .7  0 5o5‘0  t' 


.■";  :jV  j - 


■ X -c  a .!■  .Jc'  *>-•  * riv  ot  ^ .X  j.  J :r*.  ' 

X:o,  *;OXt  O':  :i:;j  'it  'I  ' - . •■?  ^ 

- ‘ - - -tq: 


-t  ao::':  otX  .!•■  o o (j  ito  crooi 


’.4  »V 


c.i  oX  ■ 0 ..i  r.-iXoitr-. 'o  (!, 


. ■:  i!” '•'■u”*  D.‘i  •'(.'•‘■'i;;  C.‘  tO  ’ * ;' 


'.rl::  r.i  rroi'-  }f;.\ 

.?..;.:0v;  '.’ViX  ut  1 X 00  -X  ol'l  rfo.:  ••  ,:i  ’'.’rf'' 

i 

I ' 0- lx X.O'ri  ’ ctX  '^COw‘  I ■>  :>.■: 


to  V o'jX  ' :.X  X o.':j  ■>  , . . 'X  ‘ o.  ::i  C:9XDlX'ii»  .'.  XnJ  - oo'i  'J  c7  5.'!f 


Xto-ro*  rol.r:  rl  0313  " ’ - “ ^ i - X-cr  rlorilil 


loe  I 


sink  was  12,  per  cent*  In  retesting  the  float  it  was  reiimnersed  in 
the  same  solution  immediately  after  the  first  separation  and  allowed 
to  remain  only  ten  seconds  in  order  to  avoid  as  far  as  possible  in- 
crease in  specific  gravities  of  the  material  by  absorption  of  water* 
These  tests  show  that  the  separation  between  heavy  and  li^t  par- 
ticles as  they  exist  at  the  moment  the  separation  is  made  is  prac- 
tically 100  per  cent  complete  if  the  test  is  made  carefully. 

There  are,  however,  a number  of  conditions  v/hich  affect  to 
a considerable  degree  the  results  secured  by  sink  and  float  tests. 

The  most  important  of  these  conditions  are  probably  the  moisture 
content  of  the  sample  when  tested,  the  length  of  time  of  immersion 
of  the  sample  in  the  solution  and  the  thickness  of  the  layer  of  raw 
coal  formed  by  the  sample  when  placed  in  the  vessel  in  which  the 
test  is  made. 

Several  extensive  studies  have  been  made  on  the  subject 
of  specific  gravity  of  coal.  At  the  U.  S.  Geological  Survey  fuel 
testing  plant^,  which  was  operated  in  St.  Louis  in  1904,  specific 
gravity  determinations  v;ere  made  on  ei^i^ty-two  samples  of  central 

f! 

district  coals.  The  average  value  obtained  for  clean  coal  was  1.29  p 

li 

and  for  average  raw  coal  1.34. 

Nebel^  made  an  extensive  investigation  of  Illinois  coals 
determining  the  specific  gravity  of  samples  under  different  condi- 
tions as  regards  moisture  content. 

Ordinarily  two  figures  are  given  for  the  specific  gravity 
of  a coal,  one  designated  the  ^apparent"  specific  gravity  and  the 


^U.  S.  Geol,  Survey  Bull,  323. 


Sta.  Bull.  89. 


'Specific  Gravity  Studies  of  Illinois  Coals,  Eng.  Exp. 


109 


other  the  “true”  specific  gravity.  The  apparent  specific  gravity 
is  the  specific  gravity  of  the  coal  including  the  moisture  or  air 

ei 

I 

contained  in  its  pores.  The  true  or  "real”  specific  gravity  is  the  1 
specific  gravity  of  the  actual  coal  substance  corrected  for  air  and  | 
moisture  content.  In  determining  this  value  the  weight  of  the  mois- 
ture per  cent  is  deducted  from  the  weight  of  the  coal  and  all  air 
is  removed  from  the  pores  of  the  coal  by  boiling  before  it  is  weigh- 
ed in  v/ater. 

In  coal  v/ashing  it  is  the  "apparent"  specific  gravities 
of  the  individual  particles  as  units  including  impurities,  pore  , 
space  and  whatever  is  in  the  pores  at  the  time  the  coal  is  fed  to 
the  washer  which  is  effective  in  bringing  about  a separation.  For 
this  reason,  from  the  practical  point  of  view,  the  "true"  specific 
gravity  does  not  enter  into  the  problem  of  coal  washing, 

Nebel  made  specific  gravity  determinations  on  freshly 
mined  coal  containing  the  natural  vein  moisture  and  on  samples  of 
air-dry  coal  after  immersion  in  water  for  varying  periods  of  time. 

His  work  led  to  the  conclusion  tlnat  the  coal  in  place  in  the  bed  is 
saturated  with  water,  and  that  air- dry  coal  immersed  in  water  in- 

I 

creases  rapidly  in  apparent  specific  gravity  during  the  first  hour,  j 

I 

This  shows  that  in  making  a sink  and  float  test  the  effective  spe-  \ 
cific  gravity  of  the  material  will  increase  gradually  from  the  in-  | 

stand  the  sample  is  immersed  in  the  solution  and  particles  will  be  | 

|l 

continually  leaving  the  float  and  joining  the  sink.  Nebel’ s tests  | 
showed  increases  of  from  0,02  to  0,03  in  specific  gravity  during  thej 
first  five  minutes  of  immersion  in  water. 


I 


■ • ■ -r  ;)  J "Hi  ’Z.'  '• 


r-* 

X -. : . ' 

] '»I,fx  A ^ ; ^.n 

..  -■  ' or. 

: 0 •>  -> 

'Ci,  0 

X or’ 

• * V ^ . ' M s.  S 

'..Oit  vu 

• •►-  uc  I.  '■' 

X^i:J  n 

1 ^ 

. u:  ' 

V *\’  O ft 

■•  ' /■A  s ,.  *• 

•'t  > 

.* 

J!  Ti,  MiTn  40:1 

•Iff;; 

- 1 • 

.-A  — V.  ■*  - 1'  ■ 

. , • r \ 

. X 

' • * ^ ."1  < 1 ■• 

ft  in 

».  A 

oy::6X' 

- ft  * 

t 

- ■ 1 ♦ 

t . ^ **-^  .* 

iuXo»rt  mTi.i.: 

#;  ^'■ 

• ■ :v  Ic'iii  i}. 

' ♦ Ta  ' ' 

T . X t<. 

; f-.-'J 

'K 


.~oL^ 


•/JJ  ; ^ 


•ii  ' ni 


*:■ 


Si^C.-  V»^.  •.'  X 


■'■  .'i  ilOXC’’  ’ t.*'.  A?  £iJ  r.,.'00  '■*'  - M li  »‘ 

— ^ ,'  ■ «»  ~i_T 


J rr  I ••■:  :■  i.  i . O M. ' * 0 J"  ft.'.  3h  (■ 


J.'llccr  J,  ’O:  - X4  .,*;'^ 

» ' -.  .Li  ..  OD  ij  ^.1  ■ . I.  •.  : ' ' X 'i 

: a'lcl*  ,y  vj  o*'t*  . 

- •■  ■ -^Xtlicr  '•-  iX  ;7:  3v:  •':*■•:  C, : rrj;  <,;  v r_v;:>..iT  -v  , .!.  .^D  « 

. 'I  .0  ";.i  :*  -/-■ -• 

^ ■-■  i SD'il./  .:i  I«£ 

•ri  l ic-j 

. • J iS  \>  S. '.  ' .j. 

•j- 

'■-  • " - -I? T r. ;-.  r I i ■ ' j;  J; 7 ns,' 

..  A...'  n^i.u r ft."  .'.oisTt/Xo^  - i-.L  ir? 

■ 9fU  ',  L,  ..  a.c 

' .'i  i''.  XtinrrQ  n*-  -♦  ofi  . 


£/4' 


n 


. .A*  V'  fi- 


^ ' fij  r? 


f. 

I 


'1 

:ir'viAjoq~  ri' 


. I » * 


^ . f ‘ 4 - 

- 1^  li  T 


ii  , A ^ .51  ^ ri.'*  i tx 


9tU 


i- 


anewLjm«3i>»3m  liiijliat: 


, . V' 

a:  A 


110 


More  recently  T.  J.  Drakeley^  determined  the  effect  of 
drying  under  various  conditions  on  the  specific  gravity  of  lumps  of 
coal.  Samples  of  wet  freshly  mined  coal  continued  to  lose  weight 
for  586  hours  when  exposed  to  the  air.  After  this  time  the  specific 
gravity  varied  with  the  hygrometric  state  of  the  atmosphere.  The 
maximum  variation  in  the  air-dry  sample  being  from  1,2008  in  a steam 
heated  laboratory  to  1.2261  during  a period  of  wet  weather  when 
heating  of  the  laboratory  was  suspended. 

Tlie  size  and  shape  of  the  vessel  in  "yihich  the  sink  and 
float  test  is  made  will  also  affect  in  a measure  the  results  attain- 
ed, It  is  apparent  that  two  duplicate  samples  of  the  same  size,  one 
of  which  is  tested  in  a tall  narrow  vessel,  and  the  other  in  a wide 
shallow  vessel,  will  not  give  identical  results.  More  time  will  be 
required  for  the  separation  to  be  completed  in  the  tall  vessel  and 
on  the  other  hand,  more  difficulty  will  be  experienced  in  removing 
separately  the  sink  and  the  float  products  from  the  shallow  vessel. 
The  important  point  in  this  connection  is  to  make  the  maximum  size  j 

i 

of  sample  treated  small  enough  in  proportion  to  the  size  of  the  veo-| 

sel.  The  thicker  the  layer  of  raw  coal  in  the  solution  when  tested  | 

I 

the  more  chances  will  there  be  for  li^t  particles  of  sink  to  be  I 
enclosed  in  and  carried  up  by  the  mass  of  float  particles  and  vice 
versa. 

These  investigations  show  the  necessity  of  standardizing 
the  conditions  as  regards  moisture  content  of  sample,  time  of  im- 
mersion and  apparatus  used  in  making  sink  and  float  tests. 

^Coal  Washing,  Further  Scientific  Studies,  Colliery 
Guardian,  March  12,  1920, 


•T' 


3 


r'  »• 


J,;-  ;c*v  -^T^©i  «)'i 


■'i.T-,  o'Wo-  i rr'J"  lie  /^r:v^Jl^^..  !»L'oJt"t^.'.,«^'- 


11 


) ’ 


• « r- 


: .'  - , •^'tUr  v)  r^oepea 


C;  '"j  J 


• r.o'iv.VTf 


jTTi  ^«*r 


• -iJtr 


ct't  r rr  l^d  r:c* 


-•  O'  ' -::i  ,. 


•>’V  rA»t  .,>'-* 


•j.  oC'.: 


Tic-rs*:v:'  : -j*  ♦ io  r^rXJ-  ^ 

K*'  ' ' 


‘ !i  ty.i 

^1 


• /'  w f -^,^11^  i , :>,•  ~T  Sf'<'  ’ :.  . 

' '-C1  1)'.*  o;. -!.?):’  4 ;u  ^f.i!  \r, 

' - . ^ ■■  '■  ~-*  . L — j :'  :i  •.wOt'*  'oiijE©  ■ 

••'’’’  --'■  - ;.»Di:  ;•  r;  > 

V ■>  ‘ - f 


■?•  -.A^j  o>.;  >i  -•■.  f-^t'  .',.  utiiyy’Z.y 


- -•  WOi.I  i,':  ;- 
i : ; ■C'iiii 

r ri.  . >.,  • ; y,  ...  r^".  , ., 

• . r*.  ^ • » * - » • J U>  * V 0 

--•^v  '::  c:;.;  «o^,  ^ ,,  .,  ...  ■^, 

al  ff  *n.‘ y<^'  4,*..'  ■ * 'J' 

^ - ' '>3  IT : i . , .i;o-x ,•;  .X I ...(r, , r o r ’i  J X . aJ  - l-.o ; 

j...  -iC'i  w •_  ,o  .vs?y.:!X  oiii  'ii!  ir  ir*,  n’ " 


■K 


. • »{f  - . 


i V 


'J  J-.W  - .';  »/i;.,  a . ot  •.'•r-);;.  T.rj,.  ' ■T»fn*!.i5iVo 


j 


Iv  f,:v.  - ^ ; ,.jX1 


:?jj4j.:  o.'' 


-.-Xfco  &xi  -3  i X.  •'£ 


t> 


•ti 


r.  V" 


-Xi  I -;r;,vjf>»i  y.f?  v;;n’«  n vj  .;  ,->v 


■*<  " ;3 

- -.-T,..  CT..«SiO.„  C.  ‘ O j ; * >T  .io*5  ■ , , J 


•-toJ  3M0l'y  ;:.:  :..,i  • ; ,.x  . n> 


.•  . f 


I 


: j.  i : 


^ ' i i I M f?;*  >.  ■-,  .•'..' ,.»J ’U ' tUi  • . .' 


^ I 


»«%>* 


Ill 

These  are  conditions  which  can  only  he  fixed  arbitrarily 
as  there  is  no  one  naturally  correct  method  of  procedure.  For  these 
reasons  the  sink  and  float  test  is  a method  of  analysis  which  must 
he  carried  out  very  carefully  in  order  to  he  of  any  real  value, 
moreover  it  is  a method  which  is  easily  misused  to  misrepresent  the 
facts  about  the  operation  of  a machine,  as  it  is  possible  to  secure 
most  any  result  desired.  Therefore  it  is  just  as  essential  to  know 
the  conditions  under  which  a sink  and  float  test  was  carried  out  as 
to  knov;  the  results. 

At  pra.ctica,lly  all  commercial  washeries  the  raw  coal  after 
crushing  goes  throu^  raw  coal  storage  bins  which  hold  several 
hours  or  perhaps  several  days  output  of  the  plant.  The  coal  when  it 
is  fed  to  the  washer,  therefore,  is  usually  in  a more  or  less  air- 
dry  condition.  Largely  for  this  reason  the  air-dry  condition  v/as 
adopted  as  standard  for  ssmplos  for  the  sink  and  float  tests  in  this 
study.  The  time  of  immersion  was  fixed  at  sixty  seconds  after  and 
not  inclusive  of  the  time  used  for  stirring  the  sample  in  the  solu- 
tion to  thoroughly  wet  it.  This  is  sufficient  time  to  allow  the  | 

sink  and  float  particles  to  come  to  their  respective  positions  and  | 
yet  sufficiently  short  to  minimize  the  effect  of  absorption  of  solu-l 

5 

} 

tion  by  the  coal  particles.  In  tests  carried  out  in  large  glass  | 

i 

cylinders  the  solution  intervening  between  the  float  product  and  |i 

1 

the  sink  product  appeared  to  have  come  to  approximately  a state  of  | 

fi 

equilibrium  after  sixty  seconds,  althou^  there  is  always  some  move-l 
ment  of  particles  of  intermediate  density  in  this  part  of  the  solu-  | 
tion.  I 

In  the  Delamater  apparatus  which  was  used  for  tests  on 
samples  of  coal  coarser  than  one-fourth  inch  in  size,  the  maximum 


ft*: 

i 


, V. 

I 

t r*  • 


. V 


ni 


■-..or  •>  Tr.  ^ o:;;  i>.i  ..r-.r:r  z^-  : -v.,  /i 

- *'•  ''  ■ - . Cu  'J  arfv*  V..J  ii.;,j:il' 

j’;.--  +.,0;':  yfi?  i't'iOv*i:.'  ■','. i . 

; i;  ' • " 

iO  w ..  : • ; . ;.t  . ’’i.  :o’4  *■  M oJ  <nr70-’  ■:;  V .»•{  c- 

J V*  C'- 2’^  . lil  Lt'  u.:)  l':.  . H'  lO'j'r 


-f*.'  -■  ; or*  ‘i... 


i.r*  .-i  U.oi  lb  js« 


•?.?»-  Vji/O'  •£  >,-.V 

•^:  . 1 ri'. . 1*'-  - 


. C X.  * J 

' ot  n ':?^u4  k'v  ' 

.^xio 

tvj’v?  r'f'iie'i.Ci  r 

i lb 

• .’Zx  , . i 

* ^ 

;>  ’ 

O.J 

1 


kiiti 


k ■'i 


% ill 


112 


li 

! 

size  of  sample  treated  was  2500  grams.  In  the  cylindrical  machine 

used  for  fine  coal  up  to  S/S"  maximum  size,  the  largest  samples  | 

1 

treated  were  400  grams.  In  each  case  this  gives  a maximum  thickness  1 
of  . coal  in  the  vessel  of  three  inches. 

The  important  thing  in  making  a series  of  sink  and  float 
tests  in  the  examination  of  a washery  is  to  fix  upon  a definite 
standard  set  of  conditions  and  maintain  them  consistently  throu^out 
in  order  that  the  results  may  be  comparable. 


SAMPLING  FOR  SINK  AND  FLOAT  WORI^ 


The  sampling  of  coal  for  a sink  and  float  test  is  more 
difficult  than  sampling  for  chemical  analysis,  because  the  coal  as 
tested  must  be  at  the  size  at  which  it  is  washed  and  cannot  be 
crushed  before  quartering  as  in  sampling  for  analysis.  Larger  sam- 
ples must  therefore  be  taken  and  they  must  be  handled  as  little  as 
is  consistent  with  accuracy  in  order  to  avoid  breakage,  which  by 
disengaging  refuse  from  coal  affects  the  results  of  the  test. 

Blythe  and  O’Shea^  in  an  investigation  of  coal  washing  in 
the  British  fields  made  sink  and  float  tests  on  a number  of  dupli- 
cate samples  in  order  to  determine  hov/  large  a sample  must  be  taken 
to  give  accurate  results.  They  also  made  tests  with  colored  coun- 
ters mixed  together  in  various  proportions  and  came  to  the  oonclu-- 
sion  that  a minimum  of  two  thousand  particles  is  necessary  in  order 
to  keep  the  mean  probable  error  within  0. 5 per  cent.  On  this  basis 
the  minimum  weight  for  various  sizes  of  coal  is  about  as  follows: 


^The  Examination  of  Coal  in  Relation  to  Washing,  Trans. 
Inst.  Min,  Eng.,  LVII,  p.  261. 


" rriTCUitf  t :r  :.^. 


b iiu'ir.* 


1 

r.i  W .Cyj- 

■:.  *1  -'’  ; 

• C lx' 

■■  ; I'  ■? 

c.  .•/.' 

■C.  oy  ■ 

I - o1 

. f - tt  t' 

♦ m 

CO*- 

s’xr'"  •••x^ 

•vf 

|.  - • ■ * ' ■- < j-  J.'l  : .'  od^  Ili  i*CO  , 

, ,U-.  ...,w.  ..Via  to  Jivl-.  .3  « iiJ  S;:itf;  : :,.j.*,.  ,,  ■T 

-"  . I 0 ro-..v  T.f',  oi  ai  v.ortL.p  ■ , 'io  ..ci,  ;.,t,'is.:  ■ o..:  cj 


-'71' J"  ■ ‘ ' 


r!  c ' 


•VwJ  ;—r.  t.toi^ ion&>  -r>:  b-r;D 

•, -:oo  D-:;  ASVt..  *i^tc  »:] 


^IFIOTt  I . 0.;”^.  ,.  iti..i'I  /' 

-.iw  3 .-. f ., ■-- ->' 


;■  -ii.'^:« 


t 4.i*oi>  .’j;;,,  ;.,  ’ -j,!)!  r!::r*^  *Xi.»r  ’ •>  J| 

1 :' .'..t.'iJ-'Cj-  ;:  ...^  _ , v .:  ' . '*>fi  J 

- ....  aw»2.*, -jj  J'  j-^  «cfj-^^,f;'i:r  - 


■ " ’) 


«:\.Ih;.’t.  'io'.i  ri  e-^  ;,r:/-H.-:  .v  - ‘"I 

* '■  - - - A.U  ..  W . i,  L 


. ..  ■♦^  - •'  'r.- 

'■“*  ■-•■■•--  Orf  f>-:  .’ioiii  • • SKUCt^s^iSq 

■“'  ' ■ f.i:c'V  0^  - OW.IU  vo>.ti;:  y • .c^'^  i^r  i , . ^ : r.oy.  eiT  n 

I.OD  -ri  . u-'t.;.  - J, , .j.  ' 

- XaJo  Tc  rroi^<--.:;i^cevfU  ctu'r.Jt  X-;$'  iln-  nr/^vM 

. ^ ^ io  *.f.  j.  .jf  v„  w-Cii-  jfrtiv  .•.'.  .;»5x7.  dnitliZ 

•vli*  3^r  a>  r^C^noj..  o»:i3 

fV 


-::i;cy  ■ oioloo  ,L:1.-  c^.:c^  sh. ocU  vs*j:'  , i £ u y 3.1  y*  > 

--i-j;.-.  Ov.  1..;^  Ow  e..T’  ':.>  'j:c?  ^ oi-  ;3£.'x..v'  nl  loxi^o-u.*  fe^iri;:  r ;r...t  ' * 


:x£  -0  r?x  &1  zo£ijJ:‘i:y  ; Ixteetforf.^  owj  1':'  'awai.t-i'/a  .«  .-t.rfj-  acxn  .iS 

..0  •X;^.,  ..  10M3  sl^.fvid'oiji  ;:4©;;-  g.'j'  qeek  i>. 

,.^Ql  f;,:  ::i  ixioo  ■ i ; i;j;:lc'  3UCi*x.:v  'lqI  ;trf£io:7  ;^fci^^:£T  ^.i.r 


,',.  irrc  'iiv  o?  :'i  £ oO  1c 


• , X V S , t ^ Jt  , ' f 


113 


Size  Inches  Weight  ^Tirams 


- 1/10  10 

1/16  - l/e  50 

1/8  - 1/4  200 

1/4  - i 1000 

Over  i 20,000 


Tliese  investigators  apparently  did  not  give  due  coneidera- 
tions  to  the  difference  in  the  nature  of  various  coals  as  it  would 
appear  that  the  accuracy  of  sampling  would  depend  more  upon  the  net 
amount  of  the  smallest  constituent,  that  is,  on  the  wei^t  of  sink 
in  the  sample,  assuming  that  the  sink  is  the  smaller  product,  than 
upon  the  gross  wei^t  of  the  total  sample  taken.  For  example,  if 
the  total  amount  of  raw  coal  to  he  sampled,  contains  only  one  parti- 
cle of  sink,  no  sample  less  than  the  entire  lot  would  he  perfectly 
representative;  on  the  other  hand,  if  the  raw  coal  were  approximate- 
ly half  sink  and  half  float  and  v/ere  perfectly  mixed,  a sample  con- 
sisting of  only  a few  pieces  would  he  representative.  From  theo- 
retical considerations  it  appears  that  the  minimum  -size  of  sample 
which  can  he  used  depends  upon  the  necessity  for  compensating  errors 
due  to  imperfect  mixing  of  the  sample  and  on  the  proportion  of  the  | 
smallest  constituent  being  determined,  j 

On  all  the  coals  used  in  this  study,  preliminary  sink  and  || 
float  tests  were  made  on  duplicate  samples,  taken  in  the  usual  man-  j 

Ij 

ner,  in  order  to  detemine  the  variation  from  the  average  in  deter-  j 
minations  on  samples  of  the  size  used.  In  addition  to  this  precau-  \ 
tion,  in  1919  a general  investigation  of  this  subject  was  made  using 
a coal  from  the  Sharon  Mine  in  the  Danville  district  in  Illinois  and  I 
one  from  Ramage,  West  Virginia,  The  Sharon  coal  was  a hi^  ash 
screening  containing  a comparatively  large  percentage  of  free  dirt, 
such  as  is  used  at  the  University  of  Illinois  power  plant  and  the  i 


u 


C'.f 


» ;n 


nV  - >• 


J . . jw  r. 


^ \ •» 
wv« 


OOu 

oct.r 


^ V - ■ "V 

~ V 


-ot)innoo  ^lr^  ^ ton  I:^3vni  seaxiT- 

^/4IOf/  .?/  •,  'ii  '-  uii  wXXOi'lJtT  ■ Ci  im/ifii**  9;\^  j '■‘t'Tt  ii  ^ ■ - 

.:aa,  OTtoi"  X L’-’ 


^iiJi'X^rieo  \o  \;o or.J 


■ w 

. “ w * I « 

■w- 

c ■ ■ 

t ■ 

OlfJ  j 

Lv  orroo 

* 0 0 X 

■.>- 

iC  vatfOTT 

1 • 

t ^ 

h 

1 w 

* oii/ 

r • 

.*1 1 

- J 

V 

\ 

:j/aa3  of{;V.  r 

U 

- 1 

r 

•,r.o  " 

or 

■’  * - _ 

Tit,  2 

I.r 

\*c* 

9r‘  • 

■t  -'tn  } rrf  ■ 

-.  . 

*^r->  orii  rrjqi 

■ ■■  ‘i 

O': 

:o 

\Xao 

• 

. • .%  ■ . w 

• 

- 

r~  •i 

V 

C.'.:i)0  r 

.'•!X  re  ;»:• 

AUXt; 

i.  lii^Jor'  f2i. 

a^" 

0 r • L. 

I'O-.- 

•»  w.'. 

* ■ ' -i" 

o/*;*!::ot3  C 

M 

‘ e 

.ic  'Vo  “ r- 

- 

'*  0 • 

* r 

• o\ : 

• r 

00  ■a'Jd'i  ‘j  .'^ 

e 

. 

'cort''  p 

c •’5'  n ; 

X-  ^ l5‘'..9'X  > -4' 

V'  ' 

- r 

n s , 

'-  j <i, 

a VI 

V'  00*:".!.) 

A rux 

'U-T. 

■ ;,!ii.Xfi  lisa 

•M. 

* ♦ 

w 

w 

^ W 

, 9 

JC'H-.OI 

i ^ ^ 

J J 

lU)n 

rereiq 

V.'O'i  V, 

;'no 

\ii  ij.niJnl: 

• ' - 

:.'  n-„‘ 

ixii, 

• . , . r-k 

>.«  ■ ■ »j 

‘'i 

'X::oc 

qji  :*  ' 

■Tr^oXv  Ato: 

;io 

"■•VO  leciv'.': 

--I  . r e;uv|'^:oy  uo>  iv'r*^  t^njn  -..-f::  no-qi;  avr'rrq./T  bo«tr  sj"  .tev  rfx/i:r{-’',f' 


_ -v  .!Oi^'i-.jo^:tr  erfj  no  -jo  av‘v:i-  *c0>xe(^r:  s*ijh,  ^ 

- ' ' iS 


* f’  -nians^ i5l/  3niif';'  J i<  >f‘j  *’d“»nco 


■*  yffs?.  IX  f!  lYj 

xi  .Z.>VB>:_prU  •:,;.  rts>;  * , :^p.  c ■.,:  ■■,Kk..;..  .-..>  «xow  q^^9^  l 

, iob  (T/  o-j!i-.v.  o.,..  aoi-.  T arti  9.ti«neJ-afl  o*  »e;)To.:  ' 

•>a'i.T  3X  -.f  .^x  noX^i  >h-.  ’I  oh.,*-  'io  fjQXi7i::^3  ri'’  - - ‘ - 

3i/  obhc:  .*j  -V  ni.-:;*  'x-.  noi«‘..'-.X .:. .'x::nr>y- 


c^oni-.  ,!  /::  -oi'i^n.V'  o^Iir;t^  s»fij  ni  o-iL'  no^.  m ©/{;  .^oi'> 


‘LQr  fr*  , * * ¥ 

«!■ 

ff-t.’.  •..  c-^  IfioD  n<yi.:Sc  o:ri  i-.^v  DO-rl  jE>rtio<^ 

'■*’  ■ ■'  ^ “‘""OiP-."!  oj/i9i  \;,tav^#o;.e'!riori  ,‘j  ,;oa  jr > n.,o':'.) a\j' 

) ;.<U  .XOV..CM,  .;io.n/!.i  io  v.‘ iflaviai;  a-'.*  690^  ,j;  .9  .icuali 


t 


S3TTf 


114 

Ramage  coal  was  a high  sulfur,  lew,  ash  coal  in  which  the  impurities 
were  largely  disseminated  throu^  the  coal  in  fine  particles.  These 
were,  therefore,  tw'O  radically  different  types  of  coal.  Results  of 
the  sink  and  float  tests.  Tables  9 and  10,  give  a further  indication 
of  the  amount  of  impurity  in  the  coal  sojnples  used. 

Samples  of  each  of  the  two  coals  as  received  at  the  labo- 

ratory emounted  to  over  two  thousand  pounds.  The  ^est  Virginia  coal 
was  sampled  at  0”  - 2”  size  by  the  alternate  shovel  method  taking 
every  fifth  shovel.  This  sam.ple  of  about  four  hundred  pounds  v/as 
then  crushed  to  size  and  divided  into  sixteen  approximately  equal 
parts  by  dividing  and  redividing  in  the  usual  manner  vdth  the  Jones 
riffle  sampler.^  Each  of  these  sixteen  parts  was  then  reduced  to 
about  one  hundred  grams  size  by  the  same  process.  These  samples 

were  used  for  the  check  sink  and  float  tests.  The  Sharon  coal  was 

sampled  in  the  same  manner  exxept  that  it  was  di\’ided  in  half  and 
one-half  was  crushed  at  once  to  one-fourth  inch  maximum  sized^and 
used  for  the  sampling.  Results  of  these  tests  are  given  in  Tables 
9 and  10  and  are  shown  graphically  in  Fig.  20  where  the  per  cent  j 
float  is  plotted  against  weigjit  of  sample  and  weight  of  sink  portion^ 
of  sample.  This  gives  the  da.ta  in  the  form  of  a probability  curve,  j 

I 

The  figures  plotted  for  the  larger  saanples  are  averages  of  tv/o  or  j 
m.ore  of  the  unit  samples  on  v/hich  actual  determinations  were  made.  | 

i 

I 

— 1 

■1 

•^Chemical  Study  of  Illinois  Coals,  S.  W,  Parr,  Illinois 
Coal  Mining  Investigations,  Bull.  5« 


4 

% 


\ 

\ 


I 

i 


i 


117 

200  grans,  as  recommended  "by  Blythe  and  O’Shea,  vrauld  be  sufficient 
for  the  0”  - size,  but  for  the  other  type  of  coal,  where  the 
present  sink  is  very  small,  a much  larger  sample  is  necessary.  Four 
hundred  grams  was  fixed  upon  as  the  minimum  for  coals  of  this  kind. 

23.  Efficiency  Formulae>  Several  methods  have  been  pro- 
posed by  different  writers  for  estimating  the  efficiency  of  a coal 
washing  operation.  All  the  formulae  which  have  been  published  are 
based  on  the  sink  and  float  test  or  a combination  of  the  sink  and 
float  test  with  chemical  analysis.  Since  the  separation  made  in 
coal  washing  depends  entirely  upon  the  specific  gravity  of  the  par- 
ticles, it  is  logical  to  take  as  the  standard  of  comparison  the  re- 
sults of  a complete  specific  gravity  separation  made  at  the  ri^t 
specific  gravity  to  give  the  products  desired.  If  the  specifica- 
tions for  the  washed  coal  require  that  the  separation  be  made  at  a 
specific  gravity  of  1.40  then  the  effectiveness  of  the  washing  op- 
eration is  measured  by  the  extent  to  which  it  approaches  perfect 
separation  at  this  point,  discharging  as  refuse  all  particles  higher 
than  1.40  in  specific  gravity  and  as  washed  coal  all  particles  v/hichf 
are  lifter  than  1.40  in  specific  gravity.  j 

i 

LINCOLN’S  FORMULA  I 

F.  C.  Lincoln^  calculated  the  efficiency  of  coal  washeriesj 

3 

I 

by  the  following  formula: 


Efficiency  = 


^ float  in  washed  coal  -(-  ^ sink  in  refuse 


This  formula,  as  explained  by  its  author,  is  useful  for  purposes  of 


P.  57. 


^oal  Washing  in  Illinois,  111,  Eng.  Exp.  Sta,  Bull.  69, 


118 

comparison.  That  it  does  not,  however,  accurately  express  the  me- 
chanical efficiency  of  the  operation  is  shown  hy  calculation  of  the 
efficiency  in  a case  #iere  no  separation  of  refuse  from  coal  is  made 
and  the  efficiency  is  therefore  known  to  he  zero.  In  this  case  the 
products  designated  as  washed  coal  and  as  refuse  would  each  contain 
the  same  proportions  of  float  and  of  sink  as  the  original  raw  coal, 
say  for  example  85  per  cent  float  and  15  per  cent  sink.  The  effi- 
ciency as  calculated  would  he 

_ 80. 4-,  ,15  «.  50  per  cent 

2 “ 

DELAMATSR’S  EORIvIULAE 

In  1914  G.  H.  Delamater^  proposed  a set  of  four  formulae 
for  calculating  coal  v/ashing  efficiencies  under  four  different  sets 
of  conditions.  Having  determined,  hy  subjecting  samples  of  the  raw 
coal  to  sink  and  float  tests  on  solutions  of  various  specific  grav- 
ities, the  solution  which  makes  the  most  desirable  separation;  the  | 

float  on  this  solution,  called  the  ’’permissible  hath”,  is  designatedj 

\ 

as  standard  washed  coal  and  the  amount  of  this  float  product  as  a | 
percentage  of  the  raw  coal  sample  is  taken  as  the  standard  yield  of  i 

i 

washed  cod.  The  efficiency  of  a washing  operation  is  then  calcu-  \ 

I 

lated  as  follows;  | 

, , I 

Condition  (Ij  where  the  yield  of  washed  coal  is 

standard  and  the  ash  content  of  the  v/ashed  coal  is  above  the 

standard.  i 

Pav;  coal  ash  - Washed  coal  ash 

Efficiency  — — 

Haw  coal  ash  - Standard  washed  coal  ash 

Condition  (2)  where  both  the  jj’ield  of  v^ashed  coal 
^Coal  Washing  Efficiency  Calculations,  Coal  Age,  May  2,1914. 


119 


and  its  ash  content  are  above  the  standard.^ 

Condition  (3)  where  the  yield  of  washed  coal  is 
below  the  standard  and  its  ash  content  is  standard.^ 

Condition  (4)  where  both  the  yield  of  washed 
coal  and  its  ash  content  are  below  the  standard.^ 

Apparently  these  formulae  are  based  on  rdec4«  0^^  t^nro  e>^* 
ficiency  factors,  a yield  efficiency  expressing  the  relation  of 
actual  yield  to  the  hypothetical  yield  corresponding  to  perfect 
separation  and  an  ash  removal  efficiency  representing  the  ratio  of 
actual  ash  reduction  to  that  secured  by  perfect  separation. 

The  numerical  average  of  these  two  efficiencies  is  desig- 
nated es  the  general  efficiency  except  in  condition  (l)  which  in 
order  to  make  it  consistent  with  the  other  three  formulae  should  be 
changed  to 

Paw  coal  ash  - Washed  coal  ash 
Efficiency  — 100 . - . . 

Rav/  coal  ash  - Standard  washed  coal  ash 

2 

While  these  formulate  are  valuable  for  the  comparison  of 
two  or  more  operations  all  of  which  come  under  the  same  one  of  the 
above  four  conditions;  efficiency  values  calculated  by  the  different 
formulae  are  not  directly  comps-rable  with  each  other,  because  the 
physical  significance  of  the  relations  expressed  between  the  differ- 
ent factors  differs  in  the  various  formulae.  In  condition  (2)  the 
yield  efficiency  is  expressed  by  the  following  relation  betv/een 

^The  formulas  are  shown  on  the  following  page. 


jyy- 


•>  - X*: 


.M 


- ^ 


-V 


' ~’^Bf 

r 

" 

t aP" 

S- 

•«  ^ 

■ -p  ™ 

■■  f,  ■■'I 

^ 'C"  » ■ ' 

'<  •'te 

“i 

Q. 

^ { 

fcv  ./•% 

. 

- 

» f 

\\  ^ 


\ r^'--  - 


•m 


3 


n 


VI 


-nr-' 


» 


0 


r» 


* ^ 

II 


■ m'  • 

■W' 

O 

y* 

- *►:  - 

n 

‘ r ^ 

• Vr 

W^j'  ' ■•* 

- 

o 

u 

■ *'  ' r ‘ ' rf*’^  .&. 

' • *:-v^  • 

u 

• - ' 

*.'-r  ■■  • ■*  ' 

,#*»'' 

iK  , 

H> 

• • '*  ■ 
• ?l  '**»i 

« t ^ 

. ^.  - ■ 1 » i - ^ 

^v- 

fVP 


i.  * 


0 


'll 


■:S 


U-JS’i 


■«< 


■wN*.'^ 


121 


actual  yield  and  the  standard  yield. 

Washed  coal  yield  - Standard  v/ashed  coal  yield 

100  - Standard  washed  coal  yield 

While  the  corresponding  part  of  fomula  (4)  is  expressed  as  the 
direct  ratio  of  actual  yield  to  standard  yield. 

Washed  coal  yield 
Standard  washed  coal  yield 

That  these  two  expressions  have  an  altogether  different  significance 
and  v:ill,  therefore,  give  values  which  ene  not  comparahle  is  ob- 
vious. 

DRAKELY»S  fiETHOD 

T.  J.  Drakely^  has  recently  suggested  a method  of  calcu- 
lating the  efficiency  of  washing,  which  is  based  entirely  on  sink 
and  float  results.  Like  Delamater* s equations  it  consists  of  two 
factors  which  in  this  case  are  designated  qualitative  efficiency 
and  quantitative  efficiency. 

V/ashed  coal  float  - Raw  coal  float 
Q,ualitative  efficiency  -g  

100  - Raw  coal  float 


^Coal  Washing,  A Scientific  Study,  Trans.  Inst.  Min. 
Eng.,  Vol.  54. 


r . , J 


122 


Q,uantit£iti ve  efficiency  ~ 

Raw  coal  float  - (Refuse  float  x percentage  of  refuse) 

Raw  coal  float 

The  general  efficiency  is  the  product  of  the  qualitative 
and  the  quantitative  efficiencies*  The  author  explains  the  appli- 
cation of  his  formulae  as  follows; 

TABLE  11 


Average  Working  of  Jig  Washers 


Raw  coal 
Per  cent 

Washed  coal 
Per  cent 

Refuse 
Per  cent 

Float 

70,25 

89.41 

2.  89 

Sink 

29.7  5 

10.  59 

97.  11 

Output 

— “ 

78.8 

21.20 

‘♦From  Table  11,  which  gives  the  average  values  for  the 
working  of  jig  washers,  .it  is  observed  that  the  concentration  of  the 
float  particles  in  the  coal  is  raised  from  70.25  to  89.41  per  cent. 
Hence  the  quality  of  the  coal  is  enriched  by  19.16  per  cent  out  of 
a possible  29.75  per  cent.  The  qualitative  efficiency  (19.16  4- 
29.75)  X 100  = 64.  4 per  cent. 

' Q-Uantitative  Efficiency.  Of  the  total  rav/  material, 
21.2  per  cent  is  lost  as  refuse,  and  of  this  2.89  per  cent  is  coal. 
Hence  coal  amounting  to  (2.89  x 21.2)  ^ 100  "0,61  per  cent  cf  the 

f, 

total  output  is  lost. coal,  Therefore,  the  amount  recovered  is 
(70,25  - 0.6l),  or  69.64  per  cent  out  of  a passible  70.25.  The 
quantitative  efficiency  (69,64  4-  70,25)  x 100  — 99,13  per  cent, 

I favour  the  calculation  being  made  as  suggested  for  the 


I 


■'D 

■ ' 'v;  '-T ' j 


«i  “ if 

: •*■  B ? ' 


■y^ 


:r 


123 


following  reason:  During  the  process  of  v/ashing,  a certain  ajnount 
of  slime  is  invariably  produced.  This  slime  is  usually,  at  the 
present  time,  a waste  product;  but  future  investigation  may  demon- 
strate that  it  is  utilisablc.  In  such  circumstances,  the  only  loss 
in  the  washing  process  will  then  be  the  coal  in  the  refuse.  The 
slime  question  is  not  settled  one  way  or  the  other,  and  until  it  is 
it  would  appear  to  be  more  satisfactory  not  to  regard  the  slime  as 
being  a total  loss.  If  no  slime  were  produced  in  the  v/ashing,  the 
tv;o  calculations  vrauld  become  identical, 

' General  Efficiency  of  the  Washing  Process.  It  has 
been  shown  above  that  the  process  recovers  99.13  per  cent  of  the 
real  coal  as  washed  coal,  with  the  quality  improved  by  64.40  per 
cent.  Hence  the  general  efficiency  (99,13  x 64.  40)  I.  100  — 63.84 
per  cent.” 

This  method  has  the  great  advantage  that  it  consists  of 
one  general  formula  which  is  applicable  to  all  cases  and  may  there- 
fore be  used  for  the  comparison  of  washers  operating  under  widely 
different  conditions  although  the  practical  utility  of  such  a com- 
parison is  a matter  of  conjecture. 

The  only  v/eak  point  in  this  formula  is  that  it  makes  no 
distinction  between  the  heaviest  sink  particles  of  pure  refuse  and 
the  li^t  particles  of  bone  which  barely  exceed  1,35  in  specific 
gravity.  In  actual  v;ashing  practice  the  heaviest  refuse  particles 
are  practically  all  removed  early  in  the  operation  and  such  sink 
material  as  remains  in  the  v/ashed  coal  v/ill  consist  mainly  of  par- 
ticles of  intermediate  density  which  have  been  described  in  Chapter 
III  as  natural  middling,  Eor  this  reason  the  figure  for  qualitative 
efficiency  calculated  by  the  above  formula  may  be  misleading  espe- 


■i  f 


i 


cJt  p. ; , J 


* 7 


f 3 


■ X C.0  .1 


\ 


*)  • : 


. • .f  • 


b 


♦ 


• 1. 


- - - •,  c u 


. } 


»'» 


- . ir  - nr'  c :■:* 


•'.•  •:> : ■ A 


•A 


f . y 


K, 


r> 


f:.'  ^ 


■ ; • • ■f*T  ^ ‘ 


i 


.l^^ 


y r\  ^ 


;m  ' '*.  ' 


'•) 


y 


‘ 


A 


^ r . • 


124 


cially  in  considering  a coal  containing  a large  proportion  of  raa- 
terial  of  intermediate  density  say  1.35  to  1.40.  A large  part  of 
this  will  go  into  the  washed  coal  and  the  effect  on  the  efficiency 
value  as  calculated  will  be  out  of  s.ll  proportion  to  its  effect  in 
increasing  the  ash  content  of  the  washed  coal.  Of  two  washers  each 
producing  washed  coal  containing  10  per  cent  sink  in  solution  of 
1,35  specific  gravity,  in  one  of  which  this  sink  is  most  all  heavier 
than  1,80  and  contains  60  per  cent  ash  and  in  the  other  lighter  than 
1.40  with  20  per  cent  ash.  The  first  is  certainly  operating  less 
efficiently  than  the  second. 

Any  of  these  fomulae  are  of  value  for  the  comparison  of 
results  secured  with  the  same  or  very  similar  coals  on  different 
machines  or  by  different  processes,  where  the  conditions  of  mining, 
crushing, storing,  etc.,  are  the  same  or  they  may  be  of  value  for 
comparing  results  secured  with  different  coals  on  the  same  machine 
to  determine  the  relative  washability  of  the  different  coals;  but 
for  universal  application  in  different  operations,  where  so  many 
variables  enter  in,  the  value  of  such  calculations  for  purposes  of 
comparison  are  doubtful. 

The  variety  of  formulae  advanced  and  the  variety  of  re- 
sulting figures  secured  indicates  the  great  difficulty  of  arriving 
at  a single  figure  which  accurately  expresses  the  true  efficiency 
of  a coal  wa-shing  operation. 

24,  Methods  Used  In  the  Study.  This  work  has  consisted 
largely  of  a study  of  the  results  securable  by  washing  coals  with 
jigs  and  v/ith  concentrating  tables.  Investigations  were  conducted 
in  the  field  at  operating  washeries  and  experimental  plants  and 
more  in.tensive  studies  of  the  operation  of  individual  machines  were 


A L 


125 


made  in  the  laboratory  of  the  Department  of  Mining  Engineering  of 
the  University  of  Illinois. 

The  use  of  efficiency  calculations  has  been  limited  to 
the  comparison  of  washing  tests  with  different  machines  on  samples 
of  the  same  coal  or  tests  with  the  same  coal  under  different  condi- 
tions as  regards  sizing,  or  for  comparing  the  results  with  different 
coals  on  the  same  type  of  machine. . For  use  in  the  field  for  esti- 
iljating  the  effectiveness  of  operating  washers  a method  v/as  devised 
which  combines  some  features  of  the  Delamater  formulae  with  some 
features  of  the  Drakely  formula. 

Having  ascertained  the  maximum  allowable  ash  in  the  washed 

coal  or  the  limiting  sulphur  content,  if  sulphur  is  the  limiting 

and  the  yield  of  float  coal  , 

feature,  this  is  designated  as  standard  washed  coal/^of  the  desired 
degree  of  purity,  determined  by  a specific  gravity  analysis  of  the 
raw  coal  is  taken  as  the  standard  yield  of  washed  coal.  The  ef- 
fectiveness of  the  operation  is  then  expressed  by  the  follov/ing: 

Actual  yield 

Yield  efficiency  or  quantitative  efficiency  =: 

Standard  yield 

Actual  ash  reduction 

Q,ualitative  efficiency  — — 

Standard  ash  reduction 

Haw  coal  ash  - Washed  coal  ash 

Raw  cop.l  ash  - Standard  v/ashed  coal  ash 

These  two  factors  are  combined  as  a product  in  order  to  reduce  the 
efficiency  to  a single  figure.  The  qualitative  efficiency  is  based 
on  ash  reduction  rather  than  reduction  in  per  cent  sink  as  in  the 
Drakely  fomula  in  order  to  avoid  the  error  due  to  difference  in 


126 


impurity  of  light  and  heavy  particles^ of  refuse.  Since  the  ash  con- 
tent in  different  particles  of  any  given  coal  varies  directly  with 
the  specific  gravity,  this  method  of  computing  qualitative  efficien- 
cy will  give  approximately  the  same  figure  as  would  he  secured  hy 
the  Drakely  method  if  a complete  specific  gravity  analysis  were  made 
on  each  product  and  compensated  values  computed  for  the  increments 

i 

of  different  densities  in  the  refuse  retained  in  the  v/ashed  coal. 

To  apply  the  Drakely  formula  in  this  manner  would  he  laborious  in 
the  extreme,  and  its  use  in  commercial  practice  would  he  impracti- 
cable for  that  reason.  Use  of  the  ash  reduction  for  this  purpose, 
hov/ever,  makes  the  desired  adjustment  automatically. 

The  standard  yield  is  determined  by  the  sink  and  float 
method  because  no  other  method  is  available  for  fixing  this  point. 
This  requires  a complete  specific  gravity  analysis  of  the  raw  coal 
only. 

The  two  factors,  yield  efficiency  and  qualitative  effi- 
ciency, are  combined  by  taking  their  product  rather  than  their  nu- 
merical average  because  each  of  these  factors  affects  the  value  of 
the  operation  independently  of  the  other;  that  is,  if  the  ash  re- 
duction approaches  zero,  althou^  the  yield  may  he  up  to  the  stand- 
ard the  efficiency  of  the  operation  approaches  zero.  On  the  other  | 

hand,  if  the  yield  is  zero  the  efficiency  of  the  operation  is  zero,  | 

I 

although  the  ash  reduction  in  an  infinitesimal  portion  of  washed 
coal  mi^t  he  standard.  In  either  of  these  cases,  if  the  numerical 
average  of  the  yield  efficiency  and  the  qualitative  efficiency  is 
taken,  the  Lincoln  or  the  Delamater  formula  will  show  an  efficiency 
of  50  per  cent,  while  when  the  two  factors  are  combined  as  a prodiAct 
the  efficiency  in  these  cases  is  shown  correctly  as  zero.  This 


127 


means  that  the  scale  of  efficiencies  runs  from  0 to  100  while  when 
the  general  efficiency  is  taken  as  the  average  of  the  yield  effi- 
ciency and  the  qualitative  efficiency  it  runs  from  50  to  100* 

In  the  experimental  washing  tests  which  were  conducted  in 
the  laboratory  where  equipment  and  time  were  available  for  making  a 
complete  study  of  the  operations,  specific  gravity  analyses  were 

made  on  samples  of  the  raw  coal,  washed  coal,  refuse,  and  in  some 

tests 

cases  of  intermediate  or  middling  products.  Screening^on  all  the 
products  of  the  specific  gravity  analyses  then  completed  the  data 
to  show  exactly  what  disposition  was  made  by  the  washer  of  each  type 
of  raw  coal  particles  as  regards  density  and  size,  which  are  the  two 
most  important  factors  affecting  the  separation  of  refuse  particles 
from  coal  particles. 


128 


CHAPTER  VII 
COAL  WASHING  TESTS 

25.  Outline  of  the  Experimental  Work.  It  was  not  the  in- 
tention in  this  study  to  go  into  the  principles  of  the  hydrosepara- 
tion of  minerals  with  an  investigation  of  settling  ratios,  rates  of 
falling  in  water,  etc. , as  that  ground  has  probably  been  as  thor- 
oughly covered  as  the  needs  of  actual  commercial  practice  justify. 
The  object  was  rather  to  examine  a number  of  typical  coals,  partic- 
ularly coals  which  have  been  found  difficult  to  wash,  to  determine 
to  what  extent  these  coals  can  be  improved  by  washing  and  to  deter- 
mine, if  possible,  what  are  the  characteristics  of  the  non-washable 
coals  which  make  them  difficult  to  wash. 

Washing  tests  with  jigs  and  tables  were  made  in  the  lab- 
oratory on  samples  of  coal  from  the  Illinois  No.  6 seam  at  Herrin, 
from  the  Bon  Air  seam  at  Bon  Air,  Tennessee,  from  Beds  ”C”  and  ‘’D’' 
in  Clearfield  County,  Pennsylvania,  from  the  Eagle  seam  of  the 
Kanawha  group  at  Ramage,  West  Virginia,  a.nd  from  the  Indiana  No.  3 
seam  at  Terre  Haute.  Of  these  five  coals  the  Tennessee  coal  and 
the  West  Virginia  coal  are  classed  as  distinctly  non-washable  and 
the  Pennsylvania  coal  as  difficult  to  wash  at  jigging  sizes. 

26.  Equipment  Used  in  Experimental  Work.  The  coal  washing 
jigs  installed  in  the  iiining  Laboratory  of  the  University  of  Illi- 
nois are  a Stewart  jig  with  a 8*  x 1-^'  P^'H,  a three  compartment  New 
Century  (Elmore)  jig  with  the  differential  eccentric,  which  gives  a 
rapid  down  stroke  and  a slow  upstroke  to  the  piston,  and  a two  com- 
partment Kartz  jig  similar  to  the  Luhrig  nut  coal  jig  illustrated 

in  Fig,  8,  This  jig,  shown  in  the  photograph,  Fig.  22,  was  used 


8 


151 


for  all  the  laboratory  jig  v/aahing  tests  of  this  study.  The  pistons 
are  actuated  by  simple  eccentrics  which  give  equal  up  and  down 
strokes.  The  length  of  stroke  and  number  of  strokes  per  minute  are 
adjustable.  The  height  of  the  final  washed  coal  overflow  gate  and 
of  the  overflow  from  the  first  compartment  to  the  second  compartment 
are  adjustable,  so  that  the  thickness  of  the  bed  of  coal  maintained 
on  the  screens  may  be  varied  by  the  operator.  The  refuse  discharge 
gate  is  of  the  pot  valve  type  consisting  of  an  opening  in  the  dis- 
charge side  of  the  jig  box  just  above  the  screen.  Inside  the  jig 
box  a vertical  half  cylinder, which  covers  this  opening,  extends 
down  through  the  coal  layer  of  the  bed  and  into  the  upper  part  of 
the  refuse  layer.  The  refuse  passes  under  the  lower  edge  of  this 
cylinder  and  out  the  gate,  but  the  coal  cannot  w'ork  down  through  the 
heavy  refuse  to  enter  the  cylinder  from  below.  The  height  of  this 
cylinder  is  adjustable  so  that  the  thickness  of  the  refuse  bed  may 
be  varied.  The  rate  of  discharge  of  refuse  from  the  jig  is  regulat- 
ed by  hand  by  varying  the  size  of  the  discharge  opening.  Each  com- 
partment, 7”  X 15**  in  screen  size,  is  provided  with  one  refuse  dis- 
charge valve,  A feldspar  bed  may  be  used  in  either  or  both  compart- 
ments. The  raw  coal  is  fed  to  the  jig  by  shoveling  into  a chute 
from  which  it  runs  by  gravity  into  the  first  compartment  of  the  jig 
through  an  adjustable  gate,  by  v^ich  the  rate  of  feed  may  be  regu- 
lated. 

The  table  washing  tests  of  this  study  were  made  on  two 
experimental  concentrating  tables  in  the  Mining  Laboratory  of  the 
University  of  Illinois  and  on  a commercial  size  coal  washing  table 
at  the  Testing  Plant  of  the  Deister  Concentrator  Company  at  Fort 
Wayne,  Indiana,  The  two  laboratory  tables  are  shov/n  in  the  photo- 


133 


graph  Fig.  23.  The  table  in  the  foreground  is  a Butchart  ta,ble  man- 
ufactured by  V/.  A.  Butchart,  Denver,  Colorado,  and  the  other  is  a 
Deister-Overstrom  table  manufactured  by  the  Deleter  Concentrator 
Company,  Fort  V/ayne,  Indiana.  The  laboratory  Butchart  table  is 
7*  6*’  long  by  3’  0”  wide,  giving  a deck  area  of  22^  square  feet. 

The  Deister-Overstrom  is  7*  3"  long  by  3*  3“  v/ide  with  a deck  area 
of  23^-  square  feet. 

The  special  feature  of  the  Butchart  table  is  the  shape  of 
the  riffle  which  has  a curved  portion  in  the  middling  zone  so  that 
the  heavy  material  moving  along  the  riffles  toward  the  concentrates 
discharge  edge  has  to  climb  in  this  curved  section  against  the  trans- 
verse inclination  of  the  table  deck.  This  facilitates  the  cleaning 
of  the  concentrate,  vfhich  in  coal  washing  is  the  refuse,  and  makes 
the  line  of  separation  of  refuse  from  the  coal  more  stationary  as 
the  coal  cannot  climb  against  the  transverse  flow  of  wash  water. 

Also  by  moving  the  load  of  refuse  farther  up  on  the  table  toward 
the  wash  water  launder,  it  increases  the  effective  area  of  the  clean- 
ing zone  and  increases  in  a measure  the  capacity  of  the  table.  This 
effect  is  most  apparent  in  the  treatment  of  coals  containing  a large 
proportion  of  refuse.  A similar  effect  is  secured  on  the  Plato 
table,  manufactured  by  the  Deister  Machine  Company,  by  making  the 
concentrates  climb  against  an  inclination  of  the  surface  of  the  deck 
in  the  middling  zone  corresponding  to  the  curved  riffle  portion  of 
the  Butchart  deck. 

The  Deister-Overstrom  table,  which  is  the  other  machine 


shown  in  the  photograph,  secures  an  increased  capacity  and  cleaning 
area  by  the  diagonal  deck  feature.  The  deck  of  this  table  is  shown 
in  the  drav/ing,  Fig.  24.  The  raw  coal  feed  box  and  middling  dis- 


Fig,  24A-  Coal  Washing  Table  Showing  Special  Equipment  Used 


^ - 


136 

charge  are  at  opposite  corners  on  the  long  diagonal  so  that  the 
middling  particles  and  unseparated  coal  and  refuse  particles  have 
to  travel  the  maximum  distance  before  being  discharged  as  middling. 

As  Bhowi  in  the  illustration , Fig.  22, the  tables  in  the 
laboratory  discharge  their  products  into  galvanized  tanks.  From 
these  tanks  the  v/ater  and  coal  are  piped  through  the  floor  into  set- 
tling cones  from  which  the  settled  coal  and  refuse  are  drawn  off 
into  steam  heated  drying  pans  for  sampling  and  v/ei^ing.  The  tanks 
are  divided  into  compartments  so  that  three  products  can  be  made  in 
the  Butchart  table  tests,  and  four  can  be  made  in  tests  on  the 
Deister-Overstrom  table.  The  division  points  between  the  various 
compartments  are  adjustable  so  that  any  desired  separation  nay  be 
made. 

In  order  to  make  an  intensive  study  of  the  disposition 
made  by  the  table  of  the  various  kinds  of  particles  as  regards  ash 
and  sulfur  content  these  two  tables  were  equipped  with  a series  of 
spouts  along  the  refuse  and  the  coal  discharge  edges  to  guide  the 
discharging  material  into  a number  of  separate  sampling  cans  or  com- 
partments. The  arrangement  of  this  special  equipment  on  the 
Deister-Overstrom  table  is  shown  in  Fig.  23.  The  coal  and  refuse 
discharging  around  the  side  and  end  of  the  table  may  thus  be  divided 
into  twenty  products  varying  in  quality  from  the  cleanest  coal  to 
the  cleanest  refuse.  The  divisions  were  made  closest  together 
around  the  middling  corner  of  the  te.ble  because  this  is  the  region 
in  which  the  separation  between  coal  and  refuse  is  made.  Somewhat 
similar  equipment  was  used  by  Richards^  in  making  a study  of  the 

^Text  book  on  Ore  Dressing,  p.  343. 


•».  1 


... 

• 

nzoin-zn 

0 Ts'O 

y ^*4***S^, 

- . - . k ..  i.^i, 

J;  - <51' 

a.’* 

■ ■‘l  i~.  1 ' ':.< 

In* 

c>;jXaJ 

•ta.**'  ...  ’ . • -.  V* 

'i  ■ . ' 2'£  « 

.0  iv^ 

c X ••■■■, 

i "ir:i 

:i":  .!* 

• *'  •>  * /•  ./  - V 

- J - a - ... 

« • 

« 

-"f' 

r.  .1 

•T.-Oria 

■V  '''  ':'.  X •'1/.'  ’.'  I a' . 

T J’o:; 

1. ‘If,  xj.vl 

*•  * 

i.v'.j’on 

' ^ .'y  • * D 

ot  . 

I a a 

• r fS  'V 
*•  . > w 

■■  - * O '. 

•7,  :^ 

.)v.  '.  4*t  £'  . 

f 

* . i ' > 

j-'V'  J,,.? 

4J  A ^ « 

V Cto't' 

U--J  :co  ^ailJ  -die 

''': iX ms -10. £ bt>:  :j 

. J : oa  -V'  : ^roo^err}/.  ’>3;?i:Trii>' C'£ 

••■*  ^ rii.r  ■xi  c*'  Xifis— , UM  " ■*«■  ci  w‘-.:  u^T 

I . . . 

• ■ *>cf , 1.  f . IX  crj  <•' X ! ',rj  ! ' c>fl-  . ■ ■STO'x ,?  c'>;s 


/ ~ 0/  i vji.  , eifj  iX 


.-.n 


• ' ■- * 'SC  .rrxxf-  r - ^ ic^  v'%•'J^  r'^5,+  fr;  .:-!  ^yij^cr.  Q.f  -rcib-s-  nl 

■ " * 'ic>  r„-.-ti^  Drti  lo  <s:^  V.f.,.,  ■ 

b'v  ..  ;yp^  ^,-  . o.*  : ..Snoo  l>r.  P 


■ IS? 


r);-. 

ox  o;-x-  ■0tI^ 

X : 00  6iO  _’...-  s 

. C'  X ^ t X i ' W , f i 

.*  '£- 

-..••10  ■. 

• 'XOc^-.:;;-,,  . el'll  Xr.i'Trtj; 

- Y ‘ X:,iiv.':o.«ib 

is» 

- - i:.  X V • X :jra^  :■ 

'to  : T < '•  .Yf.^*-.  .j/ 

; ;x  ‘met: 

■’.  ^.; : L^cj  o:  i ,f  , * . 

ij  i.  / > : : .■  * *r  . ..-. 

- <:l  -i  yi 

/ ax;.:j  - .i:  .iijx;X  t -'X  '1  o 

, ' 

■•*  ■ .;.'i:'  orr^,. 

■ 

OX 

''.O  *f‘D.Tj.3.' •;  ;)•'■*■  irtO',’: ' vXx 

■ 'i;  ni  '3 j.  . •▼  c_X  p o 'i 

■ 'cXri  ’X  CX::.*^ 

. .'  ••■:  c :*  .X  2 0 T ■'  ' :':  n-r  •'■' 

i.. /if-v  Q ''  . ‘’'Irt 

v*’»Ji:-." 'y  . O 'si 

I.::,  ^•: 

; arfx  nl  nlji'  e.::tf 

"X  j-iX  lo  iorrioo  7 i’iXpoxar'  Or~f„‘  b/nro*! 

-'■'  • ' ."X  ai  b.;-"'.  X,..uo  naov.’X^^ 

> 

rloirir  ni 

....  ...  r . " ' 

^ ; ,£.x i)d8i.'  :;.cwr  ■‘rttJirf^iL'pr  jj'' 

/ 

'■,^‘C  ...  *c'u-*''S[I  ©*xO  no  ioco' 


137 

operation  of  the  Wilfley  table  on  a quart25  galena  ore. 

C' 

27.  Comparison  of  the  Work  of  the  Experimental  Table  With 
That  of  the  Commercial  Size  Table.  In  order  to  determine  what  value 
ni^t  be  attached  to  the  results  secured  in  tests  on  the  laboratory 
size  tables,  tests  on  duplicate  senples  were  made  on  the  full  size 
table  at  the  Deister  Concentrator  Company’s  testing  plant  and  on 
the  Deister-Overstrom  table  in  the  Mining  Laboratory.  These  tests 
were  made  on  an  Indiana  coal  crushed  to  one-fourth  inch  maximum 
size.  Results  secured  with  the  full  size  table  are  given  in  Table 
12. 


TABLE  12 


Results  ! 

Secured  by  Trei 

atment  of  an 

Indiana  Coal 

on  the 

Commercial  Size 

Deister-Overstrom  Table 

Weight 

Per  cent 

Per  cent 

Per  cent 

Product 

pounds 

of  feed 

ash 

sulfur 

Raw  coal 

6444 

100.0 

16.  5 

3.85 

7/ashed  coal 
( Coarse) 
Sludge^ 

5238 

81.  5 

6,9 

3,38 

374 

5,6 

32.3 

2.  26 

Refuse 

832 

12.9 

63.7 

5.9  5 

Sample  of  washed  coal  including  sludge 
Same  calculated  from  sludge  and  coarse 

8,6 

washed 

coal 

8.  55 

.05  check 


Rate  5;^  tons  per  hour. 


The  results  of  the  test  on  the  small  laboratory  table 
were  given  in  Table  4 end  Rig.  5 of  the  chapter  on  coal  washing 
principles.  The  separation,  which  most  nearly  duplicated  the  work 


^The  Sludge  is  fine  coal  and  dust  draining  from  the  v;as?ied 
coal  as  it  is  elevated  to  the  storage  bin  by  a dewatering  drag  con- 
veyor. 


13  8 

of  the  large  table, was  between  samples  13  and  14  giving  a yield  of 
85.7  per  cent  of  washed  coal  with  an  ash  content  of  8.7  per  cent 
and  sulfur  content  of  3.33  per  cent,  as  compared  v;ith  a yield  on  the 
large  table  of  87.1  per  cent  of  washed  coal  v;ith  8.6  per  cent  ash 
and  3.42  per  cent  sulfur. 

This  indicates  that  the  laboratory  size  table  will  do 
about  as  good  work  in  ash  and  sulfur  reduction  as  the  commercial 
size  machine.  The  capacity  of  the  small  machine,  hov;evsr,  is 
slightly  smaller  in  proportion  to  its  size  than  that  of  the  large 
machine.  The  tonnages  treated  in  the  laboratory  tests  varied  from 
1200  pounds  to  one  ton  per  hour,  while  the  commercial  size  table, 
which  has  approximately  five  times  the  deck  area  of  the  experimental 
table,  handles  from  five  to  eight  tons  per  hour.  There  is  also  a 
difference  in  the  size  of  material  which  the  tv;o  tables  will  handle, 
as  the  large  table  will  treat  successfully  a feed  crushed  to  a max- 
imum size  of  one-half  inch  round  hole,  while  the  largest  size  that 
the  laboratory  table  will  handle  efficiently  is  three-eighths  inch. 

26.  Tests  On  Herrin  Coal.  The  sample  of  Herrin  coal  as 
received  at  the  laboratory  consisted  of  three  inch  screenings  ana- 
lyzing 12.2  per  cent  ash  and  2.7  per  cent  sulfur.  The  visible  im- 
purities consisted  of  pieces  of  pyrite  bands  and  lenses  as  much  as 
one  inch  in  thickness;  thin  hard  shale  bands,  of  the  kind  that  do 
not  disintegrate  in  water;  a small  amount  of  fine  clay;  thin  plates 
of  pyrite  in  joint  fissures  and  an  unusually  large  showing  of  cal- 
cite  and  gypsum  in  thin  flakes. 

Tab!|.e  13^  showing  the  bands  of  impurities  occurring  at 


^Analyses  of  Coal,  U.  S.  Bureau  of  Mines  Bull.  22,  p.  513 


139 


two  places  in  this  mine  where  face  samples  were  taken  by  Bureau  of 
Mines  engineers  will  show  the  kind  of  impurities  that  hare  to  be 
washed  out. 

TABUD  13 


Sections  of  No.  6 Coal  Bed  at  Herrin,  Illinois, 
Big  Muddy  No.  7 Mine 


Section  A 
Feet  Inches 

Section  B 
Feet  Inches 

Roof,  shale. 

Top  coal  (a) 

1 

7 

— 



Coal 

0 

7 

0 

6 

Su Iphur  ( a ) 

-- 

— 

0 

Mother  coal 

0 

i 

— 

— 

Coal 

0 

7 

0 

8 

Shale,  regular  parting 

• • 

— — 

0 

1/8 

Mother  coal 

0 

1/8 

— 

— 

Coal 

0 

11 

1 

3 

Mother  coal 

- - 

— 

0 

1/8 

Shale  and  mother  coal 

0 

Coal 

1 

8 

1 

3 

Sulphur 

— 

0 

1/8 

Shale 

0 

Vs 

— 

Coal . . . 

— - 

1 

6 

Mother  coal 

0 

1/8 

0 

1/8 

Coal 

1 

4 

1 

7 

Blue  band  (a) 

0 

1 

0 

2 

Coal . . 

2 

0 

2 

0 

Floor,  fire  clay. 

Thickness  of  section 

8 

9 7/8 

8 

111- 

Thickness  of  coal  sample 

7 

1 7/8 

8 

9f 

Of  the  2.7  per  cent  of  sulfur  in  the  avera^ge  raw  coal 
used  for  the  tests  0.8  per  cent  was  in  the  organic  form  and  1.8  per 
cent  was  in  the  pyritic  form  with  a trace  of  eulfa.te  sulfur.  Sam- 
ples crushed  to  finer  than  one-ei^th  inch  and  ca,refully  ha~nd  pick- 


ed, using  forceps  and  a magnifying  glass,  to  discard  all  particles 
showing  a trace  of  impurity  on  the  surface,  still  contained  an  aver- 


140 


age  of  4,0  per  cent  ash  and  1^0  per  cent  pyritic  sulfur. 

The  mine  from  v;hich  this  coal  came  is  on  the  edge  of  the 
low  sulfur  coal  basis  of  i’ranklin  and  Williamson  Counties  as  mapped 
out  by  G.  H.  Gady^  who  designates  the  mine  samples  as  averaging  be- 
tween 1,25  and  1.50  per  cent  sulfur.  Car  samples  and  washery  head 
samples  taken  at  this  mine  at  different  times  varied  from  less  than 
one  per  cent  to  as  high  as  three  per  cent. in  sulfur.  This  shows  how 
erratic  and  uncertain  is  the  sulfur  content  of  this  coal.  This,  ac- 
cording to  the  reports  of  coke  oven  and  gas  plant  operators  who  have 
attempted  to  use  Southern  Illinois  coals,  is  typical  of  the  Franklin 
Williamson  County  low  sulfur  coals.  The  greatest  advantage  of  wash- 
ing such  a coal  would  be  to  make  the  ash  and  sulfur  content  more 
unifo rm. 

For  the  washing  tests  the  coal  was  crushed  in  toothed 
rolls  to  pass  a one  inch  round  hole  screen  and  separated  at  one- 
fourth  inch  size.  The  over-size  i-**  - I”  in  size  was  washed  on  the 
experimental  jig  described  above,  and  the  under-size  0“  - in 
size  was  washed  on  the  Butchart  table.  Results  of  these  tests  are 
shown  in  Tables  14  and  15. 

^ines  Producing  Low  Sulfur  Coal  in  the  Central  District, 
111,  Geol.  Survey  Bull.  23. 


141 


TABLE  14 


Jig  Washing  Test  on  Herrin  Coal  at  i”  - 1”  size 


Product 

Weight 

pounds 

Per  cent  of 
raw  coal 

Per  cent 
ash 

Per  cent 
sulfur 

Raw  coal 

385.0 

100.0 

11.0 

2.70 

Washed  coal 

344.0 

89.  5 

7.7 

1.89 

Middling 

5.0 

1.  3 

36.  5 

5.85 

2nd  Hutch  ( Slud, 

ge ) 8.0 

2.0 

16.2 

3.77 

Refuse 

18.8 

4.9 

48.5 

10.90 

1st  Hutch 

2.0 

0.  5 

80.  2 

2.  69 

(Pine  refuse) 

98.  2 

Loss  1.8 


TABLE  15 


Washing  Test 

on  Herrin  Coal;  0**  - -4" 

size;  Eutchart  Table 

Product 

Weight  Per  cent  of 

pounds  raw  coal 

Per  cent  Per  cent 

ash  sulfur 

Raw  coal  205.0  100.0  14.2  2.70 


V/ashed  coal 

161.0 

78.  5 

7.2 

1. 

85 

Middling 

16.0 

7.8 

19.8 

2. 

56 

V/ashed  coal  & 

Middling 

177.0  ^ 

86.3 

8. 1 

1. 

90 

Refuse 

13.  0"^ 

9.  5 

72.1 

10. 

75 

Loss 

4.8  ' 

In  these 

tests  the 

jig  showed  a 

washed  coal 

yield 

of  89.  5 

per  cent  v/ith  an  ash  reduction  of  29  per  cent  and  a sulfur  reduction 


of  30  per  cent,  vhile  the  table  showed  a yield  of  86.3  per  cent 
with  an  ash  reduction  of  43  per  cent  and  a sulfur  reduction  of  30 
per  cent.  The  raw  coal  feed  on  the  two  tests  was  not  identical  in 
ash  content  so  that  the  tests  are  not  perfectly  comparable,  but 
taking  this  fact  into  consideration  the  degree  of  separation  secured 
in  the  tv/o  tests  is  about  the  same.  The  greater  reduction  in  ash 


142 


and  the  lower  yield  in  the  tatle  test  are  exj^lained  by  the  higher 

I 

ash  content  of  the  feed.  The  efficiencies  as  compared  v^ith  sink  / 
and  float  separation  taking  float  on  solution  of  1.35  specific  grav- 
ity as  standard  v/ashed  coal,  are  67  per  cent  for  the  jig  test  and  /j 
69  per  cent  for  the  table  test.  / 

A complete  specific  gravity  analysis  of  the  0”  - raw  ^ 
coal  is  given  in  Table  16.  ^ 

TABLE  16 


Specific  Gravity  Analysis  of  Herrin  Coal  at  0”  - size 


Specific  Gravity 

Per  cent  of 
- B&jnple 

Per  cent 
ash 

Per  cent 
sulfur 

Lifter  than  1.30 

73.35 

4.64 

1.72 

1.30  to  1.35 

8o74 

11.27 

2. 14 

1.35  to  1.40 

4.93 

17.78 

2.39 

1.40  to  1.45 

1.82 

20.32 

2.  52 

1.45  to  1.50 

0.39 

24.60 

2.62 

1.50  to  1.60 

1.12 

29.90 

2.80 

1.60  to  1.80 

2. 13 

49.  53 

3.  43 

Heavier  than  1.80 

7.  52 

84.04 

13.63 

In  order  to  more  easily  interpret  these  figures,  graphs, 
Big.  25  and  Fig.  26,  have  been  drawn  to  show  the  distribution  of 
impurities  in  the  coal  according  to  density.  Beginning  at  the  top, 
the  ordinate  line  is  divided  into  parts  proportional  to  the  percent- 
ages of  the  different  specific  gravity  products  beginning  with  the 
lightest.  The  total  length  of  the  ordinate  ajcis  thus  represents 
the  total  weight  of  raw  coal  100  per  cent.  Midway  of  the  ordinate 
for  each  specific  gravity  increment  of  the  sample  its  average  ash 
or  sulfur  content  is  laid  off  as  the  abscissa.  Vertical  lines 
drawn  throu^  these  points  gives  a graph,  showing  the  distribution 
of  ash  or  sulfur  in  the  raw  coal,  and  the  area  between  the  graph  and 


< 


( 


l -i' 


« 


O’! 


r 


i! 


I 


1 i 


1 


ti 


! 


\fhrc^nt  'Yi\€>ld 


1 


145 


the  axis  shows  the  weight  of  ash  or  sulfur  in  the  sample  of  weight 
100.  The  mean  abscissa  is  the  raw  coal  ash  or  sulfur. 

The  purpose  of  this  curve  is  to  determine  where  to  make 
the  separating  line  aA,  Fig.  26,  between  the  refuse  and  clean  coal 
in  order  to  obtain  best  values  for  *‘Y"  yield  of  clean  coal  and  for 
“X“  ash  or  sulfur  content  of  clean  coal.  Obviously  there  is  a func- 
tional relation  beWeen  *'X”  and 

Plotting  the  curve  of  X^,  X. Y for  ash  and  sulfur  gives 

Yn 

the  curves  of  Fig.  26,  which  show  what  yield  corresponds  to  any  re- 
quired ash  or  sulfur  content  and  what  ash  or  sulfur  content  may  be 
secured  in  any  proportion  taken  as  clean  coal  on  the  basis  of  sink 
and  float  or  theoretically  perfect  separation.  These  theoretical 
yield  curves  are  cftlled  the  ‘*Float-ash  curve  and  the  float- sulfur 
curve’*. 

The  float-ash  curve  on  the  Herrin  coal  shows  a yield  by 

sink  and  float  separation,  of  91  per  cent  of  coal  of  an  ash  content 

equal  to  that  of  the  washed  coal  of  the  table  test,  namely,  7.2  per 

cent.  As  the  washing  test  yielded  78.  5 per  cent  of  v/ashed.  coal 

this  shows  a recovery  of  or  86.2  per  cent  of  the  good  coal  of 

9 1 

this  quality  present  in  the  raw  coal.  Comparing  the  yield  of  washed 

coal  plus  middling,  making  a washed  coal  of  8.1  per  cent  ash  content 

86  3 

with  the  float-ash  curve  shows  a recovery  by  washing  of  or  93.8 

92 

per  cent  of  this  material  available  in  the  raw  coa,l. 

29.  Bon  Air  Coal.  For  the  tests  on  co8-l  from  this  seam  a 
sample  of  run  of  miine  coal  from  the  Eastland  Mine  of  the  Bon  Air 
Coal  and  Iron  Company  was  used.  This  sample  as  received  at  the 
lg.boratory  in  Urbana  was  of  rather  fine  size*  89.5  per  cent  passed 
throu^  a two  inch  round  hole  screen.  Analysis  of  a moisture-free 


146 


sample  showed  a sulfur  content  of  4.87  per  cent  and  15.5  per  cent 
ash.  Notwithstanding  this  high  ash  and  sulfur  analysis,  visual 
examination  showed  very  little  free  dirt.  This  indicates  that  the 
impurities  are  intimately  mixed  with  the  coal. 

The  object  of  the  experimental  work  on  this  particular 
coal  was  to  detemine  to  whst  extent  the  sulfur  content  can  be  re- 
duced. Several  years  ago  attempts  were  made  to  loY/er  the  sulfur  in 
this  coal  by  washing  with  jigs,  in  order  to  produce  a more  suitable 
coal  for  the  Bon  Air  Coal  and  Iron  Company’s  coke  ovens  at  Eastland, 
but  these  attempts  were  unsuccessful.  The  experiments  made  at 
Urbana  constitute  a second  attempt  to  produce  a low  sulfur  coal  by 
using  newer  and  more  improved  methods  of  washing. 

The  results  of  screening  tests  given  in  detail  in  Table 
17  shows  the  sulfur  to  be  very  evenly  distributed  through  the  sizes 
and  that  nothing  is  to  be  gained  by  screening  out  either  the  coarse 
or  fine  sizes.  Sink  and  float  tests  made  on  these  sized  products 
and  on  original  raw  coal  samples  crushed  to  one-half  inch  and  one- 
fourth  inch  maximum  sizes,  using  zinc  chloride  solution  of  1.  45 
specific  gravity,  all  showed  very  poor  results  in  the  way  of  ash 
and  sulfur  reduction,  the  float  in  every  case  analyzing  three  per 
cent  or  more  in  sulfur  and  over  eleven  per  cent  ash.  This  shows 
conclusively  that  due  to  the  high  residual  ash  and  sulfur  it  is  im- 
possible to  make  a hi^  grade  coking  coal  by  washing  this  material. 


, I ' 1 n>-  . II  ‘ ^ -irfj  i wje!f  . 

V '*  f.'  -iii.-tl  ^i:,}  , 'ziL'  -:'r‘  ^'  oila  .-.rii^sir"  •< 

, ' O’j  'v  ■•*;•'  ; ■■::x  ’.'i  r ■ i . , j ■, 


•■i-i  n 


T-r'i:**: ! .•  •■  r*?  .;-.  . C.  :* 


lo  io»:,  ;P  ';riT 


-wrj! 


' ' .'.-.0  *.iii C^J  u:/  i^oo 

’-.  .'Llun  o.ii  -if*’  oX  uJ  . o;:>:  J t<»v<  . 

,r- 

Dl^'.  J '.  :•;  o-iv..  'Di:'  0':q  < T^^-xo  ‘ .uJiXt  xv.^  5 Pi 'iswW  •>;  ■ -OOG 

, J i*i  -.ryvo  o::Ci'-  : ' Y/’.i^'.fiGC^'  r il  &ii>  1 • •;.;>  -xi^  ''.o'l  \ V lol  I>.:oo  j|^l 

w*  •.  '*'•;  K.t . -i.i,  «,.  ’ .E;»G:>ifQi;j  Sir  vj.  9e«Jfw  ^ 


'.. : KCi  .-.I  b ;3vr;/xiJ?rroo  " 


I '.r.  - 


* ^ I c coc^j:' 9vo":GJiJt  G'loa  ^ n : *rnr»->rt  tini  jp 


I’.X ;' iV.  ..I  11  =r-:-  ’,  Cv.pd^'  3T.i.-:';^£.''io<n  Tto  L’'*i^ao-i  A,  - 1 


"'■•Gi-'r  -X  i::  ro'i.io  U0w'i,\Xi  1 *Pbb  \Irirv9  ■ i9y  3cf  cj  vx®  c v c ''S ’I*!  ■ - 4 

. **  - ^'ri 

0’‘*x  'O')  " ‘I'll  Oio  ■*"0  :rin  '0'xa‘3  '*c  . i.tAy  s>»f  Ow-  nl  on  da.:'.'X  bu.  ^ 

^ " %a 

.0.>O.L'  0’XO  o.,Oi‘f:r  i;.>  n.r’  >LnXr  .'J-rlb  o:ii%  ': ;:  ^ 


-■  "X  :X  - .po  Oc*  ivT  -j  •-jIjxGuiO  /.•‘..''G  IsnX:  ii'j  no  on  ; ^ 

♦ . “io  ncis  /I’  • jbxToXi'P  oaivT:  , ,n.,i'"  :;:  * . .rGi-.l  i"J-rj:ol  }f 

:^.-:  r • -nv/  b:id  rl  «0:i.O','r:  v^o;*  Oj  .-c'Cft  .*  ,x-iv”n'b  g^  iXo-bir*  | 

'<•-  t f:X;:v,j.^. '.  ^ *cp  ni  J'noX':  ^ i-j’tXus 

f' 

Gui'0,1in  . Xlf*'  . b*^  J ;00  •29'^  il»VOX*'  Tf*'w  b fl.  •Xu'i'XjjT  :'i  9JXi’.  'i X 1f>n 

■-.;1  clJ  .Xi  i£/ifUG  Gf.  ' Xi't-x  LiiUbik6‘i  .'•■  .in  opj  oj  bj'O  J :-riJ  vX«  .'i jnXonoo  i; 


;il''J  XX  ui  ^ vffiPtjnw  I.:o»  jiniioo  ni-  i:'  o •■  . ii bOOp 


147 


TABLE  17 


Screening  Test  on  Bon  Air  Run  of  Mine  Coal  as  Received 


Size 

Weight 

pounds 

^ of  total 

% sulfur 

On  2“  round  hole 

5.  24 

10.  5 

4.44 

On  1”  round  hole 

14.  52 

29,3 

4.  46 

On  -h**  round  hole 

11.  40 

23.2 

4.93 

On  round  hole 

8.30 

16.7 

4.41 

On  l/8*'  round  hole 

4.  56 

9,  2 

4.  41 

Through  1/8“  round  hole 

5.  50 

11.1 

4.20 

Head  sample 

49.  52 

100.0 

4.  87 

Sink 

and  Float 
Used 

TABLE  18 

Tests  on  Bon 
1,45  specific 

Air  Coal  Solution 
gravity 

% sulfur 

% sulfur 

Sink 

% float 

in  float 

% sink 

in  sink 

1" 

- 2« 

92.  6 

3.34 

7.4 

18.80 

- I” 

88.  5 

3. 12 

10,9 

17.08 

Xii 

88.  0 

3.07 

12.0 

14.  40 

1/8“ 

- 1“ 

87.6 

3.17 

12.4 

13.  37 

0« 

- 1/8” 

82.  5 

2.99 

17.  5 

9.95 

0«  - i” 

( crushed) 

90.  5 

3.22 

9.  5 

20.7 

0»  - 

( crushed) 

92.  1 

3.  51 

7.9 

21.7 

As  a visual  examination  showed  very  little  visible 
coarse  pyrite  and  these  sink  and  float  tests  indicated  an  advantage 
in  the  fine  sizes,  of  a higher  yield  of  float  coal  and  cleaner  ref- 
use in  the  sink,  the  entire  sample  was  crushed  to  a maximian  size  of 
three-eighths  inches  before  washing.  Table  19  gives  the  results  of 
a complete  specific  gravity  analysis  made  on  the  raw  coal  at  this 
size.  The  float-ash  and  the  float- sulfur  curves  are  shov/n  in  Fig. 


27 


i 


i 


V 


I 


r ♦ 


fi  i 


I 


*< 


o: 


' 

i 


c.  a 


Fe^rce^nf  'F/  <z-ld 


4.  <6 


i 


i 


149 


TABLE  19 


Specific  Gravity  Analysis  Bon  Air  Coal  at  0”  - 3/8“  Size 


Specific  Gravity 

Per  cent  of 
total 

Per  cent 
ash 

Per  cent 
sulfur 

Lighter 

than  1. 26 

16.3 

7.8 

2.  44 

1.26  to 

1.30 

39.6 

10.6 

3.01 

1.30  to 

1.35 

20.  5 

13.3 

3.35 

1.35  to 

1.  40 

11.8 

15.4 

3.  45 

1.40  to 

1.45 

3.8 

19.1 

4.39 

1.45  to 

1.  50 

1.8 

22.  5 

6.18 

1.  50  to 

1.60 

2.  1 

27.6 

9.20 

1.  60  to 

1.  80 

1.1 

42.7 

13.30 

Heavier 

than  1. 80 

3.0 

60.  5 

34.  12 

Float  on  1.45  was  designated  as  standard  washed  coal  in 
this  case  "because  above  this  point  the  curve  shows  a rapid  increase 
in  sulfur  and  ash  content  v/ith  increasing  specific  gravity  and  to 
reject  any  material  lifter  than  1,45  would  result  in  only  a small 
reduction  in  impurity  for  a large  loss  in  yield  of  washed  coal. 

Part  of  the  sample  was  washed  on  the  experimental  jig 
with  an  artificial  bed  of  feldspar  in  each  compartment.  The  other 
portion  was  treated  on  the  Beister-Overstrom  and  the  Butchart  con- 
centrating tables. 

Results  of  the  tests  are  given  in  Tables  20,  21  and  22. 


r 


s 


‘J 


•nttrz'Siar. 


150 


TABLE  20 


Feldspar  Jig  Test 


on  Bon  Air  Coal 


Heads 
15.15^  ash 
0"  - 3/8'*  size 


166  lbs. 

4*87%  sulfur 

rate  1660  lbs.  per  hr. 


r~ 

Clean  Coal 


First  Hutch 


Second  Hutch 


1 

Loss 


144  lbs. 

86.9  % of  feed 
3.8^  sulfur 
13. 37^  ash 


6 lbs. 

3.6  % of  feed 
22. 3 % sulfur 
49.  52^  ash 


5 lbs. 

3.0  % of  feed 
10,63^  sulfur 
30.975^  ash 


11  lbs. 

6. of  feed 


151 


iH 

CM 


E-t 


O 


<0 

H 

,Q 

o5 

EH 

n 

o 

^1 

02 

fn 

<U 

> 

O 

0 

•H 

0 

fi 

c 

O 

-P 

0 

0 


r-r 

d 

o 

o 

fn 

•H 

<: 

s:J 

o 

pq 


• 'CS 

W 0 
^ 0 
tH 


O 

■P 

cd 


0 

rQ 

rH 

^0 

• 

!>■ 

CO 


•d 

0 

0 d 
'h  Vh 

fH 

o 0 


CO 
O Oi 

• • 

sj«  to 
^0 


•d 

0 Jh 
0 d 
Ch  «h 

Vh  d 
O 0 


A 


•d 

0 fH 

0 d 
tH 
I — I 

tH  d 
O 0 

lO 

lO  o 

• • 

H to 

CM 


0 

d 


<j>  CO 

O to 

• • • 

H to  r-l 
CM  rH 


0 

0 

tH 

tH 

O 


o 


0 

rQ 


CM 

CO 

0 

0 

O 


> 


u 

d 

tH 

iH 

d 

0 

c- 

o 

• 

CO 


*d 

0 

0 

tH 

tH 

o 

o> 

CM 


•d 

0 fH 

0 d 

tH  tH 
iH 

tH  d 

O 0 

>-<a  v.'^ 
CO 

0> 

• • 

^ CO 
r- 


fn 

d 

tH 

iH  = = = 

d 

0 

l>  iH 

to  0> 

• • • • 

CM  CM  CM  to 


rH  CM  CO 

0 

iH 

P« 

CO 


0 


d 

d 

P< 


d 

•H 


O 

iH 

tH 

U 

0 

i> 

o 

CiO 

fj 

•H 

H 
■ — I 

o 

p 

ci3 

o 

p 

0 . 

0 0 
p f> 
o 

0 ^ 
^ d 
p 

wS 

d fn 
•H  tiO 
H d 
d -H 
'd 

d d 

0 o 

d d 
p p 
c 

0 rd 
0 02 

•H 


Pi  0 


0 0 


•d 
0 -H 
02 
0 

rd  0 
Eh  0 

o 

d 

•H 

(U 

t> 

<U 

^7» 

r» 

•P 


152 


TABLE  22 

Bon  Air  Coal  Test  on  Butchart  Table 


Feed  159  lbs.;  15.155^  ash;  4.87%  sulfur. 
Size  0”  - 3/8 ; rate  79  5 lbs.  per  hour. 
235  r.p.m. 


Ho.  1 coal  87  lbs. 

54. 6%  of  feed 

11.3%  ash  3.02%  sulfur 


Refuse  13  lbs. 

8.2  % of  feed 
17.74%  sulfur 
43.39%  ash 


No.  2 coal  51  lbs. 
32.0  % of  feed 
5.  22%  sulfur 
17.9  5%  ash 


86.6%  of  feed.  3.82%  sulfur 


Loss  8 lbs.  5.2% 


153 


In  both  table  tests  it  was  very  difficult  to  detei-mine  the 
proper  line  of  separation  betv/een  coal  and  refuse,  as  very  few  pure 
shale  or  pyrite  particles  separated  out.  The  refuse  from  the  first 
table  test  looked  like  coal  and  63  per  cent  of  it  floated  on  1.40 
specific  gravity  solution. 

In  the  second  table  test  a small  refuse  product  was  taken 
and  this  contained  a much  smaller  percentage  of  coal.  Only  20. 5 
per  cent  floated  on  1.40  specific  gravity  solution,  but  the  second- 
ary coal  in  this  test  was  much  dirtier  than  in  the  first  table  test. 

The  impurity  in  this  coal  is  not  present  as  shale  and 
pyrite  pieces  but  as  impure  particles  of  high  ash  and  sulfur  content, 
and  in  order  to  produce  the  cleanest  product  possible,  namely,  3.0 
per  cent  sulfur  and  about  11.0  per  cent  ash,  it  is  necessary  to  take 
out  a large  percentage  of  the  raw  coal,  consisting  of  these  impure 
coal  particles,  with  the  refuse  or  intermediate  products.  By  this 
means  a reduction  in  sulfur  of  38  per  cent  may  be  secured  in  a No.  1 
coal  product  amounting  to  55  per  cent  of  the  raw  coal.  This  shov;s 
the  impossibility  of  producing  a hi^  grade  coking  coal  from  this 
material  by  any  process  of  mechanical  separation.  Analysis  showed 
an  organic  sulfur  content  of  1.16  per  cent  which  precludes  the  pos- 
sibility, even  if  all  the  pyritic  sulfur  could  be  eliminated,  , of  pro- 
ducing a coal  lower  in  sulfur  than  1.16  per  cent. 

Comparing  the  jigging  test  with  the  table  tests,  it  is 
evident  that  the  two  methods  were  about  equally  effective  in  making 
a clean  separation  as  the  jig  test  and  the  second  table  test  both 
give  washed  coal  products  amounting  to  86.6  per  cent  of  the  feed 
and  analyzing  3.8  per  cent  sulfur.  In  the  first  table  test  no  prod- 
uct or  combination  of  products  comparable  with  these  were  taken. 


154 


The  efficiencies  as  compared  with  sink  end  float  separation  at  1,45 
specific  gra.vity  are  56.0  per  cent  for  the  jig  test  and  the  second 
table  test# 

The  yields  secured  in  the  washing  tests,  by  comparison 
with  the  yield  of  equivalent  products  by  specific  gravity  analysis 

shows  recoveries  as  follows; 

86.  6 

In  the  jig  test  — - = 89  per  cent 

97 

In  the  first  table  test,  considering  the  combined  No.  1,  No. 

76.9 

2 and  No.  3 coal, — rs  82  per  cent 

94 

Tests  On  Glover  Run  Coal.  The  shipment  of  Clover  Run 
coal  on  which  the  exx)erimental  work  was  done  was  received  from  the 
two  mines  of  Madiera  Hill  and  Company  at  Mahaffey,  Pennsylvania. 

A careful  visual  examination  showed  very  little  free  pyrite,  but 
considerable  amounts  of  carbonaceous  shale  a,nd  slate.  When  received 
the  coal  had  been  crushed  to  such  a size  that  98.5  per  cent  of  it 
passed  through  a one  inch  round  hole  screen.  It  contained  an  aver- 
age of  one-half  per  cent  moisture,  12.8  per  cent  ash  and  3.48  per 
cent  sulfur,  consisting  of  2.77  per  cent  pyritic  sulfur  and  0.71 
per  cent  of  organic  sulfur.  Sulfate  sulfur  was  entirely  absent  or 
present  only  in  minute  traces.  The  sample  was  secured  by  mining, 
by  hand,  from  five  to  six  hundred  pounds  of  coal  from  each  of  ten 
working  faces.  These  portions  were  then  crushed  by  hand,  thoroughly 
mixed  and  reduced  by  coning  and  quartering  to  about  2,500  pounds. 

In  order  to  gain  some  idea  as  to  the  size  at  which  this 
coal  might  be  most  successfully  washed  and  to  determine  roughly 
what  percentage  of  the  raw  coal  should  be  removed  in  the  refuse  and 
in  the  middlings,  in  order  to  produce  a good  clean  coal,  screening 


155 

tests  and  specific  gravity  tests  were  made.  Results  are  shown  in 
Tables  23  and  24. 

The  data  in  Table  23  were  secured  by  hand  screening  a 
representative  sample  of  128.5  pounds  on  half  inch  and  o,uarter  inch 
round  hole  screens  and  analyzing  the  sized  products. 


TABLE  23 

Sizing  Test  on  Clover  Run  Coal  as  Received 


Size 

Weight 

pounds 

^ of  total 

jS  ash 

fo  sulfur 

O’*  - i'* 

62.  5 

48.  5 

10.42 

3.  56 

^ Xh 

36.  5 

28.4 

12.  46 

3.40 

- 1« 

27.  5 

21.6 

16.27 

3.64 

Over  1“ 

2.0 

1.5 

— 

To  tal 

128.  5 

100.0 

12.  80 

3.  48 

Bor  the  sink  and  float  tests,  Table  24,  samples  of  the 
sized  coal  from  the  screening  test,  described  above,  were  used.  By 
immersing  in  heavy  solutions  of  zinc  chloride  the  samples  were  di- 
vided into  three  classes  of  material;  Particles  lifter  than  1,35 
in  specific  gravity;  those  between  1.35  and  1.60  in  specific  grav- 
ity; and  those  heavier  than  1.60  in  specific  gravity.  These  repre- 
sent approximately  the  clean  coal,  middling  and  refuse  naturally 
occurring  in  the  rav/  coal  samples.  Tlrie  percentage  of  each  of  these 
three  classes  of  raa.terial  with  their  ash  and  sulfur  content  in  each 
size  of  rav/  coal  is  showxi  in  Table  24. 


156 


TAELS  24 


Clover  Run  Coal  Gink  and  Float  Teste 


Product 

^ of  total 

% ash 

% sulfur 

Size  - 

1“ 

Float  1.35  Sp.  G. 

55.2 

7.0 

1. 19 

Middling  1.35  to 

1.50 

29.2 

17.0 

4.00 

Sink  in  1.60 

14.  5 

51.31 

13.34 

Size  - 

Float  1,35  Sp.  G. 

72.0 

5.8 

1.  23 

Middling  1,35  to 

1.60 

19.3 

22.9 

5.  30 

Sink  1. 60 

7.5 

50.4 

19.85 

Size  0"  - 

Float  1. 35  Sp.  G. 

85, 1 

4.8 

1.20 

Middling  1.35  to 

1.60 

7.3 

34.0 

13.6 

Sink  1.60 

7.6 

47.7 

19.27 

The  information  of  importance  furnished  in  this  Table  is 
in  the  figures  showing  the  percentage  of  natural  middlings,  materi- 
al between  1.35  a.nd  1.60  specific  gravity,  in  the  three  sizes  of 
raw  coal,  i.  e.  , - 1'*,  29,2  per  cent;  19.3  per  cent  and 

0«  . only  7.3  per  cent.  This  indicates  that  fine  crushing  is 
necessary  in  order  to  break  the  fine  particles  of  refuse  free  from 
the  particles  of  clean  coal,  thus  reducing  the  percentage  of  mid- 
dlings, pieces  part  coal  and  part  refuse. 

In  the  washing  tests  three  methods  of  treatment  were 

tried, 

1.  A sample  of  1292  pounds  of  the  raw  coal  was 
screened  on  a quarter  inch  round  hole  screen.  The  oversize 

- 1”  in  size  was  Jigged  and  the  undersize  0”  - i-**  was 
treated  on  a coal  washing  table. 

2.  A sample  of  383  pounds  of  the  raw  coal  was 
crushed  to  three-ei^ths  inch  maximum  size  and  v;ashed  on 
the  table. 


i ‘*J 


15B 


3.  Four  hundred  twenty- four  pounds  of  the  rav/  coal 
was  treated,  just  as  received  without  sizing,  on  the  jig. 


T/iBLE  25 

Specific  Gra.vity  Analyses  Clover  Run  Coal  at  0”  - 3/8”  Size 


Specific  Gravity 

Per  cent  in 
raw  coal 

Per  cent 
ash 

Per  cent 
sulfur 

Lighter  than  1.35 

78.2 

4.8 

1.07 

1.35  to  1.40 

3.7 

12.3 

2.  20 

1.40  to  1.45 

3,  4 

19.8 

3.  18 

1.  45  to  1.  50 

2.0 

25.  2 

4. 13 

1.  50  to  1.60 

3.2 

30.7 

4.68 

1.60  to  1.80 

2.7 

34.3 

7.47 

Heavier  than  1,85 

6.8 

57.  3 

28,00 

TABLE  26 

Jig  Test  on  Clover  Run  Coal 


Coal  as  received  with  0”  - material  removed 
674#  i”  - 1”  size 
3.  50^  sulfur  14. 10^  ash 


Middlings 


Re  f us  e 


\ 

Washed  Coal 

572  Ihs.  85^  of  feed 
2.34,^  sulfur 
11.  43^  ash 


61  IBs.  9,0^  of  feed 
4.48;^  sulfur 
16.09^  ash 

^ 


Bed  product  and  hutch 
41  IBs.  6%  of  feed 
18.29?^  sulfur 
48, 08^  ash 


633  IBs.  94^  of  feed 
2. 55^  sulfur  11*  9%  ash 


Time  16  minutes.  Strokes  172  per  minute. 

Rate  3600  IBs.  per  sq,  ft,  screen  area  per  hour. 

Efficiency  assuming  float  on  1.35  as  standard 
washed  coal  63  per  cent. 


I 


1 


Wi 


■( 


159 


vn: 


160 


TABLE  28 

Table  Washing  Test  0“  - 4“  Glover  Run  Coal 
Deister-Overstrom  Diagonal  Deck  Coal  Washing  Table 

V/eight  Per  cent  Per  cent  Per  cent 
Product  pounds  of  feed  ash  sulfur 


Raw  coal 

618 

100.0 

10.42 

3.  56 

No.  1 Washed  coal 

389 

63.  0 

5.27 

1.  31 

No.  2 Washed  coal 

120 

19.  6 

9. 10 

1.82 

No.  3 Goal 

40 

6.  5 

20.  20 

5.  30 

No.  1 and  No.  2 

509 

82.  5 

6.  17 

1.  43 

No.  1 No.  2 No.  3 

549 

89.0 

7.20 

1.72 

Refuse  . 

40 

6.  5 

48.  42 

21.73 

Loss 

29 

4.  5 

Strokes  per  minute  235. 
Time  21  minutes. 

Rate  1650  lbs.  per  hour. 


\ 


...c 


I 


H 


I 

1 


TABLE  29 

Table  ^Aashing  Test  on  Raw  Coal  Sainple  Crushed 
to  3/8”  Maximum  Size 


161 


Deis ter-Overstrom  Diagonal  Deck  Coal  Washing  Table 


Weight 

Per  cent 

Per  cent 

Per  cent 

Product 

pounds 

of  feed 

ash 

sulfur 

Raw  coal 

383 

100.0 

12.80 

3.48 

No.  1 Washed 

coal 

286 

74.7 

7.90 

1.  53 

No.  2 Washed 

coal 

45 

11.8 

17,19 

4.  17 

No.  3 Washed 

coal 

7 

1.8 

40.35 

11,41 

No.  1 and  No. 

2 

331 

86.  5 

9,17 

1.89 

No,  1 No.  2 

No.  3 

328 

88.3 

9.80 

2.09 

Refuse 

24 

6.3 

52. 13 

23.74 

Loss 

21 

5.4 

Strokes  235  per  minute. 
Rate  1915  lbs.  per  hour. 


I r.  - . 


r.'  O M 

;U'N 


. ‘C- 


V* 


‘t* 


J 


4 ' . J 


. A. 


\ 


ii 


i 


ft  . 

j 

i 


( 


I: 


> 


. »• 


, 1! 

H 


M. 


162 


Results  of  tlie  two  jig  tests  on  Clover  Run  coal  are  given 
in  Talles  26  c.>nd  27.  The  low  efficiency  secured  in  the  second  test 
v/as  due  to  the  fine  material  present  in  the  unsized  feed.  Appar- 
ently the  material  below  one-fourth  inch  ring  size  was  not  handled 
efficiently  in  this  test  and  the  sink  and  float  tests  shovi^ed  in  this 
size  a very  complete  separation  with  a very  small  middling  product, 
a high  yield  of  float  coal  and  a large  reduction  in  sulfur  content. 
As  compared  with  these  sink  and  float  results,  the  separation  in 
the  jig  v/as  poor.  On  the  other  test,  where  the  rav;  coal  was  screen- 
ed at  one-fourth  inch  and  the  fine  coal  and  the  coarse  coal  were 
washed  separately,  the  efficiency  of  the  jig  on  the  -4“  - 1“  feed 
was  63  per  cent  as  compared  with  an  efficiency  of  44  on  the  0“  - 1” 
feed  unsized.  The  average  sulfur  content  of  the  washed  coal,  fine 
and  coarse  combined,  was  1.93  per  cent  with  a yield  of  74.5  per  cent 
as  compared  with  a 72  per  cent  yield  of  washed  coal  of  2.02  per  cent 
sulfur  on  the  0”  - 1”  jig  test.  This  shows  a slight  advantage  in 
sizing  before  washing. 

The  jig  tests  on  this  coal  were  not  as  successful  in  re- 
ducing sulfur  as  the  table  washing  tests.  The  preliminary  sink  and 
float  tests  indicated  that  this  v/ould  be  the  case  as  the  large 
sizes  -i”  - and  - 1”  contained  a much  larger  percentage  of 
material  of  intermediate  density,  between  1.35  and  1.60  specific 
gravity,  than  the  finer  material  under  size.  This  is  the  materi- 
al which  forms  middlings,  pieces  part  coal  and  part  refuse,  which 
require  finer  crushing  in  order  to  free  the  particles  of  refuse  and 
coal.  All  these  tests  indicate  the  necessity  of  fine  crushing. 

In  conducting  the  table  v/ashing  tests,  from  three  to  five 
products  v/ere  made  for  analysis  in  order  to  get  as  complete  data 


163 


as  possible  on  the  separation  being  secured.  Composite  fif^res 
showing  what  the  results  would  be  if  only  two  products  were  made 
are  arrived  at  by  combining  the  products  as  desired  and  calculating 
the  average  ash  and  sulfur  content.  In  the  table  tests  division  of 
the  product  into  four  grades,  No.  1 coal,  No.  2 coal.  No.  3 coal,  | 
and  refuse,  was  accomplished  by  dividing  the  material  being  dis- 
charged over  the  end  and  side  of  the  table  at  suitable  points  as 
showned  in  the  diagrams  in  Tables  28  and  29. 

By  washing  with  the  table  the  pyritie  sulfur  content  was 
reduced  70.4  per  cent  in  the  0”  - 3/8*‘  No.  1 coal  and  78.4  per  cent 
in  the  0”  - No.  1 and  No.  2 coal.  These  reductions  of  pyritie 
sulfur  are  large  and  the  hi^  reduction  in  total  sulfur  obtained  by 
washing  was  made  possible  because  only  a small  percentage  of  the 
total  sulfur  in  the  raw  coal  is  present  as  organic  sulfur. 

The  efficiencies  were  74  per  cent  for  the  0”  - 'i*'  test 
and  80  per  cent  for  the  0“  - 3/8”  test. 

Qn  \7est  Vir,c;inia  Coal.  The  West  Virginia  coal  | 

used  for  washing  tests  was  mined  at  Ramage,  in  Boone  County.  The  | 

1 

sample  received  was  taken  by  employees  of  the  company  who  were  in-  I 

V 

structed  to  take  a sample  representative  of  a full  day*s  output  of  f 

I 

the  mine.  An  official  of  the  company,  who  was  present  when  the  s 

I 

tests  were  made,  stated  that  this  particular  sample  was  somewhat  j 

5 

hi^er  in  sulfur  than  the  average  for  coal  from  this  mine.  The  coalj 
was  very  hard  and  when  crushed  to  about  three  inches  maximum  size  | 
showed  very  little  free  pyrite  and  little  or  no  slate  or  shale.  It  | 
contained  2.48  per  cent  sulfur  and  6.81  per  cent  ash  on  the  moisturel 
free  basis.  The  mine  operates  in  the  Eagle  seam  of  the  Kanawha 
Group.  The  average  of  ten  analyses  on  samples  from  the  same  seam 

I 


164 


and  county  by  the  West  Virginia  Geological  Survey  show  only  0.79 
per  cent  sulfur. ^ 

Po  r some  time  past  this  cojal  has  been  used  by  a steel 
company  for  making  producer  gas,  the  gas  being  used  in  open  hearth 
furnaces.  Recently  variations  of  sulfur  in  coal  from  this  mine 
have  caused  difficulty  in  using  it  because  of  the  hi^  sulfur  con- 
tent of  the  gas.  The  purpose  of  the  work  described  here  v/as  to  de- 
termine v^ether  or  not  the  sulfur  in  this  coal  could  be  reduced  low 
enou^  to  make  it  suitable  for  open  hearth  fuel  upon  gasification. 

In  all  the  tests  carried  out  the  sulfur  content  of  the 
cleanest  coal  obtained  was  well  above  the  maximum  figure  designated 
by  the  operator  as  satisfactory.  The  cleanest  coal  secured  analyzed 
1.65  per  cent  sulfur.  This  product, more-over,  amounted  to  only  one- 
third  of  the  original  raw  coal  fed  to  the  washer  and  also  was  crush- 
ed to  three-eigihths  inch  maximum  size,  which  is  finer  than  is  de- 
sirable for  producer  gas  fuel.  The  sulfur  content  of  the  No.  1 
v/ashed  coals  secured  by  jigging  at  suitable  size  for  gas  producer 
use,  namely,  0”  - was  1.98  and  2.00  per  cent.  These  products 

again  represented  recoveries  of  only  84  oer  cent  and  76  per  cent,  \ 

\ 

respectively.  )\t  the  0“  - size  a product  consisting  of  91.4  per  | 

t 

cent  of  the  raw  coal  analyzed  2.06  per  cent  sulfur,  and  in  the 
0“  --3/8“  size  a product  carrying  2.01  per  cent  sulfur  amounted  to 
92.7  per  cent  of  the  raw  coal. 

The  plan  followed  in  the  examination  of  this  coal  vras 
similar  to  that  described  in  the  discussion  of  the  tests  on  the 


^V/hite,  I.  C.  , , Geo  graphical  Distribution  of  Sulfur  in 
Y/est  Virginia  Coal,  .to.  Inst.  Min.  £.nd  Met.  Br.g.  Bull,  153,  p*  2200,  j 
1919. 


165 

Clover  Run  Coal.  Table 

30  shows  the  screen  analysis 

on  raw  coal 

crushed  to  three-four ths 

inch  maximum  size  and  Table 

31  shovrs  re- 

suits  of  the  sink  and  float  tests  on  the 

sized  products  of  the 

screening  tests. 

TABLE  30 

Sere en 

Analysis,  Spruce 

River  Coal 

Weight 

Size  pounds 

^ of  total 

% ash 

% sulfur 

42 

- I"  36 

39 

6.  83 

2.  66 

33 

6.  28 

2.  42 

0”  - 30 

28 

6.  64 

2.  31 

TABLE  31 

Sink  and  Float  Tests,  Spruce 

River  Coal 

Pro  duct 

^ of  sample 

% ash 

% sulfur 

Size 

Float  on  1.35  Sp.  G. 

89.5 

4.  0 

1.78 

Middling  1.35  to  1.80 

7.  5 

26.8 

6.  40 

Sink  in  1.80 

2.7 

47.  3 

22.  21 

Size 

Float  1. 35  Sp.  G. 

91.0 

4.  0 

1.  68 

Middling  1.35  to  1.80 

5.  5 

18.7 

10.  50 

Sink  in  1. 30 

3.  3 

49.  2 

15.06 

Size  0"  - 

Float  1.35  Sp.  G. 

94.  6 

4.  1 

1.84 

Middling  1,35  to  1.80 

1.7 

26.  0 

7.00 

Sink  in  1, 80 

3.  2 

52.7 

14.07 

- - 1 

V 


\ 


fig 


•if  itxius: 


‘ ■'(f 


166 


T/3LE  32 


Specific  Gravity  Analysis,  Spruce  River  Coal 
at  0»  - 3/e»'  size 


Specific 

Gravity 

Y/eight 

grams 

% of  total 
sample 

^ ash 

% sulfur 

to 

1.25 

2369 

N 

51.2 

2.  12 

1.  15 

1.25  to 

1.  30 

1529 

33.0 

3.  68 

1.  36 

1.  30  to 

1.35 

420 

9.  1 

12.  43 

3.  55 

1.35  to 

1.  40 

44 

1.  0 

14.20 

3.  36 

1.40  to 

1.45 

43 

.9 

19.75 

4,  38 

1.45  to 

1,  50 

30 

. 6 

23.  20 

4.  41 

1.  50  to 

1.60 

39 

.9 

28.63 

5.  25 

1.60  to 

1.  80 

62 

1.3 

37.82 

5.  68 

1.80 

90 

2.0 

67.27 

17.95 

To  tal 

4626 

100.0 

In  the  washing  tests  four  methods  of  treatment 

were 

tried. 

1.  A 

sample  of 

828  pounds  of 

the  raw  coal. 

crushed 

to 

” maximura  size,  v/as 

screened  on  a quarter  inch  round  hole 

screen.  The  oversize  0” 

- •¥”  was  treated  on  a coal 

^washing 

table. 

2.  Eight  hundred  forthy-two  pounds  of  the 

raw  coal 

crushed  to  pass 

a v”  round^screen  was  ^ 

treated  v/ithout  sizing 

on  the  jig. 

hole 

3.  A 

sample  of 

292  pounds  of 

the  rav/  coal 

was 

crushed  to  3/8” 

ms.ximum 

size  and  washed  on  the  table 

4.  In 

order  to 

determine  the 

distribution 

of  im- 

purities  in  the 

coal  as 

discharged  from  the  washing 

table  and 

to  compare  the  results  secured  “by  table  washing  coal  of  0”  - 
3/8”  in  size  v/ith  results  secured  by  close  sizing,  a.  sample 
of  this  coal  crushed  to  3/8”  maximuin  size  was  screened  on 
l/8”  and  i”  round  hole  screens  and  the  three  sizes  0”  - 1/8”, 
1/8”  - i”,  and  - 3/8”  v/ere  washed  separately  on  the  con- 
centrating tables  using  the  special  equipment  for  separating 
the  product  into  nineteen  samples. 

In  conducting  tests  1,  2 and  3,  from  three  to  five  prod- 
ucts were  made  for  analysis  in  order  to  get  as  complete  data  as 
possible  on  the  separation  being  secured.  Composite  figures  show- 


^ f, 


Table  35-  Spruce  River  Coal  -0”  3/-^”  Test 


167 


• Cm 

to  O 

to 

rH  '^'d 

-»<o 

CO  CD 

o 

CM  • CD 

A 

'M'  Cm 

fH  'd 

d 0 

Cm  CD 

A 

rH  ^ Cm 

o 

d 0 

p 

-p 

• 0 d Cm 

d 

0 

0 o 

0 

fH 

0 

P 

0 

d 

d 

rHv£>  O :R 

Cm 

Cm 

-P 

Cm 

• O- 

P A 

02 

0 

\CN  »vO  • 

Cm 

d 0 

rH  ft; 

rH  lr\CM  tH 

O 

0 d 

U 

d P 

CO  CM^O 

c*-i  0 

• 

• • 

rH  0 

rOCO  O 

d P ch 
0 0 

ro 

• d Cm 

0 

0 

to  ^ O 

ffi 

0 

P o 

fH 

rH  rH  CM 

Cm 

d 

* • P 

0 

o 

CTnO  d-  • 

o 

p p mcM 

'5^ 

rH 

CO 

• 

'vO 

CO 

hJ 

iH  ri 
tiH 
rH  rH 
^ 

CO  CO 


■s^ 

-p  d 

-■  §H 

-d  o «3 

GOO 
C\J  CO  o 


o5 


OJ 

"O  fH 

0)  'i  t O 
‘ 

• G 

0}  Ch  to  Vj^ 
^ O cvj 
rH  O 

'-O  CO,  • 

rH  rH  CM  rH 


'dCO 

<D  • 
W CNJ 


OQ  >> 

to  u 
G d 
•H  'O 

'CS  o rH 

-d  o cd 

•H  O O 

t:!  CO  o 


kS 

o 

CO 


to 

f-i  tS 
G o5 
'h  <D 

• rH  02  ^ 

to  d G 

^02  tt-H 

rH  O 

>R«>- 

’LTNCXJCO'A 

• rH  ’vO 

CO  *00  • 

mrH  1T\ 


to 

'd 

0) 

si 


rH  Si 
G 02  f(H 
02  Oj  O 

»R 

•CO  rH  O 
O CJNCO  • 

O • • ^ 

C>-rHlr\OD 


0)  Jh 
<D  d 

Cm  Cm 

A 

Cm  G tn 
O 02  oi 


> 


IfN 
• O CJ^ 


rH  • • 

ON  CM  lr\ 


u 

• 

c'5, 

ro 

ICN 

1 — 1 
d 
o 
o 

'd 

0 

A 

0 

g 

d 

o 

A 

A 

fH 

u 

d 

rd 

0 

G 

ft 

d 

d 

-P 

0 

0 

fH 

0 

d 

d 

G 

0 

ro 

0 

• 

P 

o 

0 

G 

O 

Cm 

O 

-P 

• 

d 

o 

-P 

1 — 1 

Cm 

Cm 

0 • 

Cm 

■P  CT* 

o 

d 0 

G 

0 

•H 

•H 

S 0 

0 

r ^ 

d 

0 fn 

P 

0 0 • 

H->  Ph  02 

G 

d P 

O 

G 0 P 

•H  0 

S r^  O 

o 

O ICN 

G 

ON  fH''0 

0 

P +>  OO 

•H 

0 

O 

0 0 

•H 

s CM  -p 

Cm 

•H  i>-  d 

Cm 

P P !XJ 

'A 

y 


' Tti  ^ : 


Table  36  - Spruce  River  Coal  1/4“  - 3/4"  Jig  Test 


168 


.c! 

OJ 

«3 


<D 

tr\ 

CM 


03 

• C|H 
03  0 
rQ 

03 

rH  'd 

.0 

vO  CD 

ITN  • CD 

CD 

Pi  tJ 

d CD 

03 

C|H  rC  CD 

rCj 

(H  03  Ch 

0 Cm 

d «3 

+3  <U 

• 03  Cm 

03  ^0 

.►tH 

CD 

rH  OCO'^'^ 

-P  S 

1 — 1 • VPv 

03  -H 

u^  • 0 • 

rH  h) 

rH  C30  POCM 

CD 

s. 

of  feed 
sulfur 
/ ash 

03 

rQ  ^OD 

R 

rH  0 

%-\ 

0 • • 

CD 

CO  • POCV 

fR 

rH  POrH  f>0 

> 


•ri 

CD 

CD 

'h  R 03 
O 03  cc5 

lr\I>-vO 

• • • 

ITN  O 'M' 

rH  PO 


05 

CD 

u 

cd 

CD 

CD 


TzJ  fn 

0 

03  d 

03 

• C7N 

CD  Ch  ^ 

03  « 

•s  & 

Cm  rH  03 

« 

d cd 

-p 

rH 

-p  cd 

Ch  03 

Cm 

CO 

^ d ^ 

Pi  s:l 

• 

to 

0 V'i 
'^^ro 

• 

(Js  R 

■d  8 

rQ 

CH 

UN  Cm 

— ! 

C'-vO  • 

03 

1 1 

sc:  0 0 

• • UN 

xJ  d 

CM  CO  0 

'sj- 

0 CM  rH 

u 

CD  03 

CD 

o 


Pi  d 

0 

d 0 

+= 

Cm  d 0 

d Pi 

d u 

03 

>> 

iH  ra  Cm 

0 d 

d 0 

bO  U 

d cd 

0 Cm 

•H  Pi 

cd 

• 03  Cm 

Cm  iH 

B 

-*rH 

d 

0 0 

d 

0 

rH 

C 

rQ  Vi  0 

Cm  0 0 

0 P d 

'd 

0 rH 

H UNlTN*:^ 

0 cd 

0 0 d 

■d 

0 Cd 

rH  • ti — 

■p  Pid 

•H 

0 0 

CXD  • "M-  • 

d 0 

CO  0 

CM  iH  'cj- 

CJNrH  rH 

d 0 Pi 

•H  0 

CO  CMvO 

CO 

olrN 

5 

U\  d CM 

rH  -P  PPJ 

d 

0 

Pi  0 

0 0 

rH 

d CD 

S CM  -P 

W 

Ch  Cm 

•fH  CO 

0 

cH  ^ 

^ rH 

:o 

• d 03  Cm 

0 0 cd  0 

d 

rQ 

■“0 

rd 

^sOUN 

03 

00  oun  • 

cd 

0^  • • prj 

^ CM  UNCX) 

J 


Efficiency,  on  the  basis  of  float  on  1.35  as  standard  washed  coal,  45/ 


169 


ing  what  the  results  would  he  if  only  tv/o  products  were  made  are 
arrived  at  by  combining  the  products  as  desired  and  calculating 
the  average  ash  and  sulfur  content* 

TABLE  37 

0“  - 3/8“  Table  V/ashing  Test  on  the  West  Virginia  Goal 


Deister-Overstrom  Table 


Product 

Weight 

pounds 

Per  cent 
of  feed 

Per  cent 
ash 

Per  cent 
sulfur 

Raw  coal 

292 

100.0 

6*76 

2.28 

No.  1 Washed  coal 

97 

33*3 

4.30 

1.  65 

No.  2 Washed  coal 

120 

41.2 

5. 11 

1.94 

No.  3 Coal 

53 

10*2 

10*24 

2*84 

No*  1 and  No.  2 combined  217 

74.  5 

4*77 

1.81 

No.  1 No.  2 & No . 3 

270 

92*7 

5.85 

2*01 

Refuse 

15 

5*2 

30*  57 

8*90 

Loss 

7 

2.  1 

No.  1 Washed  Coal  No,  2 Coal  No.  3 


; V- 


-3 


■i 


» 


170 


TABIJi)  38 


O'*  - 1/8" 

Table  Test  Spruce 

River  Coal 

36  Per 

cent  of  0"  - 3/8" 
Eutchart  Table 

Sample 

Weight 

% of  feed 

% ash 

% sulfur. 

Product  Grams 

Cum*  ^ 

Cum..  ^ 

Cum. 

Section  No.  1 

9525 

57.  30 

57.  30 

6.  67 

6.  67 

2.03 

2.  03 

2 

SS5 

4.  10 

61.40 

4.9  5 

6.44 

1.82 

1.98 

3 

845 

5.  10 

66.  50 

4.  47 

6.  30 

1.77 

1.97 

4 

812 

4.90 

71.  40 

4.  32 

6.  15 

1,  81 

1.95 

5 

773 

4.  60 

76.  00 

4.  15 

6.00 

1.  80 

1.9  4 

6 

708 

4.  30 

80.  30 

4.  23 

5,90 

1.  81 

1.94 

7 

662 

4.  00 

84.  30 

4.  26 

5.80 

1.73 

1.93 

8 

664 

4.  00 

88.  30 

4.  38 

5.80 

1.79 

1.92 

0 

717 

4.  30 

92.70 

4.95 

5.70 

1.91 

1.92 

10 

616 

3.  70 

96.  40 

7.  08 

5.  80 

2.  19 

1.93 

11 

141 

.90 

97.30 

12.  50 

5.  80 

3.  37 

1.9  5 

12 

25 

. 15 

97.45 

17.00 

5.  80 

4.  50 

1.95 

13 

16 

.10 

97.  55 

17.87 

5.90 

4.  50 

1.9  5 

14 

78 

. 50 

98.05 

23.02 

6.00 

5. 12 

1.97 

15 

33 

. 20 

98.  25 

33.  89 

6.  10 

6.  80 

1.99 

16 

36 

. 22 

98.  47 

37.94 

6.  20 

7.  68 

1.99 

17 

26 

. 16 

98,  63 

41.91 

6.20 

8.  32 

2,00 

18 

49 

. 30 

98.  83 

46.86 

6.  30 

8.94 

2.02 

19 

198 

1.20 

100.00 

65.74 

7.  10 

16.  50 

2.  20 

16,610 

100.00 

' 

^Cum.  ~ Cumulative. 


JaC^  7 


f 


\<2.n.i~  "T^fcfd I 


■i 


172 


TABLE  39 


1/q»  - Table  Test  Spruce  River  Coal 
41  Per  cent  of  0”  - 3/8'‘  Sample 
Butchart  Table 


Product 

V/eight 

Grams 

of 

feed 
Cura,  ^ 

• 

ash 
Cura.  1 

sulfur 

Cum. 

Section  No. 

1 

JU  1 UM  — 1 ii» 

M aw 

«w  wa  aw  » 

M aw 

O 

. 23 

. 06 

. 06 

3.80 

3.80 

1.  17 

1.  17 

3 

17  5 

. 45 

. 51 

2.  80 

2.92 

1.26 

1.  25 

4 

834 

2.  12 

2.  63 

2.  60 

2.66 

1.  22 

1.  22 

5 

1891 

4.  82 

7.45 

3,  10 

2.95 

1.  40 

1.34 

6 

259  6 

6.  60 

14.05 

3.00 

2.97 

1,  39 

1.  37 

7 

3310 

8.  42 

22.  47 

3.  00 

2.98 

1.  52 

1.  42 

G 

4144 

10.  54 

33.01 

3.  10 

3.02 

1.  51 

1.45 

9 

5378 

13.69 

46.70 

3,  50 

3.  16 

1.97 

1.  60 

10 

7637 

19.47 

66.17 

4.  00 

3.  40 

2.  08 

1.75 

11 

5030 

12.  80 

78.97 

4.90 

3.65 

2.  60 

1.88 

12 

2489 

6.34 

85.  31 

5.80 

3.81 

2.  20 

1.90 

13 

615 

1.  56 

86.  87 

7.  10 

3.87 

2.  34 

1.91 

14 

1670 

4.25 

91. 12 

9.95 

4.  15 

2.  60 

1.94 

15 

1267 

3.23 

94,35 

14.80 

4.  52 

3.02 

1.98 

16 

794 

2.02 

96.  37 

21.70 

4.88 

4.  49 

2.  04 

17 

440 

1. 12 

97.49 

31.30 

5.  17 

6.  32 

2.09 

18 

230 

, 59 

98.08 

41.  80 

5,  40 

8.  10 

2.  13 

19 

779 
39 , 302 

1,89 
100. 06 

100.00 

55.60 

6.  34 

17.  50 

2.41 

Cum.  ss  Cumulative 


f^rc^nf  Tiisld  i 


-•  f 


A ' 


W:-n 


'? 


■r' 


) .- 


‘ VI*  M>k 


\.  ’,  , <■  ■; 


i;t:{ 


TiiBLE  40 

- 3/8”  Table  Test  Spruce  River  Coal 
23  Per  cent  of  0”  - 3/8”  Sample 
Deis ter-Overstrom  Table 

174 

Product 

'^feight 

Grains 

fo  of 

feed 
Cum.  ^ 

ash 
Cum.  ^ 

% sulfur 
Cumr 

Section  No,  1 

1125 

5.70 

3.70 

2.80 

2.80 

1.  66 

1.66 

2 

1188 

3.90 

7,60 

2.9  5 

2.  87 

1.88 

1.77 

3 

1465 

4.81 

12.41 

3.20 

3.00 

1.78 

1.77 

4 

1252 

4. 11 

16.  52 

3.40 

3. 18 

1.74 

1.76 

5 

740 

2.  43 

18.95 

3.  40 

3.20 

1.78 

1.77 

6 

1619 

5.  31 

24.  26 

3.  30 

3.  22 

1.84 

1.78 

7 

1455 

4.77 

29.03 

3.60 

3.  28 

1.84 

1.80 

8 

1376 

4.  52 

33.  55 

3.80 

3.36 

1.86 

1,80 

9 

874 

2.87 

36.  42 

3.90 

3.  40 

1.92 

1.  81 

10 

1449 

4.76 

41. 18 

4.00 

3.47 

1.92 

1.82 

11 

iq^ 

3.  54 

44.72 

4.35 

3.  54 

2.07 

1.  84 

12 

1800 

5.90 

50.62 

5,  40 

3.74 

2.  04 

1,  86 

13 

2897 

9.  51 

60. 13 

6.  40 

4. 18 

2.26 

1.92 

14 

50  50 

16.  56 

76.69 

7.40 

4.85 

2.  52 

2,  05 

15 

5013 

16.45 

93. 14 

10.00 

5.76 

2.86 

2.  20 

16 

1288 

4.  22 

97.36 

11.  90 

6.  04 

3.66 

2.28 

17 

201 

.66 

98.02 

18.80 

6.  10 

4.97 

2,30 

le 

576 

1,  89 

99.91 

39.  00 

6.80 

10.10 

2.  45 

30,447 

99.91 

_ 

^Cum, 

ss  Cumulative 

These 

washing 

experiments  with 

the  sink 

and  float  tests 

and  chemical  analyses  demonstrate 

conclusively  that  this 

Coal  is  a 

difficult  one  to 

wash  and  that  the  removal  of  only  the  free  dirt 

particles  in  the 

form  of 

a clean 

refuse  product  v/ill  result  in 

no 

very  ^reat  reduction  in 

sulfur. 

The  feature  of 

general 

interest 

in  this 

investigation 

is 

the  determination  of  the 

characteristics 

of  this 

coal  which  render 

it  difficult  to 

improve 

by  washing.  That 

the  trouble  is 

not  to 

be 

overcome  by  fine 

crushing, nor  by 

sizing  before  v/ashing,  ie 

indicated 

by  the  sink  and 

float  tests.  The 

separation  in  the  fine 

sizes  under 

one-fourth  inch 

is  not  a 

ppreciably  better 

than  that  secured  on 

the 

176 


larger  sizes  froia  one-fourth  inch  to  three-fourths  inch,  and  the 

combined  results  of  the  tv/o  washing  tests,  where  the  coal  was 
a 

screened  on^ one-fourth  inch  screen  before  washing,  are  no  better 
than  the  results  secured  in  the  Jigging  test  on  0”  - f-"  unsized 
coal. 

The  combined  washed  coal  products  from  the  Jig 

test  and  the  0”  - -i*’  table  washing  test  amounted  to  a total  yield 
of  83  per  cent  of  the  feed  with  an  ash  content  of  5.4  per  cent  and 
a sulfur  content  of  1.95  per  cent,  while  the  Jig  test  on  O'*  - 
unsized  feed  yielded  84  per  cent  of  washed  coal  with  an  ash  content 
of  5.3  per  cent  and  a sulfur  content  of  1.98  per  cent. 

For  comparing  the  results  of  the  table  washing  tests  on 
sized  feed  v/ith  the  test  on  0"  - 3/8"  unsized  feed,  the  separation 
between  coal  and  refuse  was  made  in  the  0"-l/8"  test  between  sam- 
ples 11  and  12,  in  the  1/8"  - test  between  samples  11  and  12,  and 
in  the  - 3/8"  test  between  samples  11  and  12.  This  gives  an 
average  yield  of  77.5  per  cent  of  washed  coal  v/ith  an  as?i  content 
of  5.4  per  cent.  The  test  on  unsized  feed  yielded  74.5  per  cent  of 
Ko.  1 plus  No.  2 washed  coal  v/ith  an  ash  content  of  4.8  per  cent. 

This  coal  is  rather  unique  in  that  it  is  high  in  sulfur, 
but  compara.tively  low  in  ash,  and  that  v/hile  the  sulfur  is  very  re- 
fractory, the  ash  is  easily  removable.  This  is  an  exception  to  the 
old  rule  of  thumb  that  the  sulfur  follows  the  ash.  The  commonest 
difficulty  met  v/ith  in  coal  v/ashing  is  a large  percentage  of  ma- 
terial of  intermediate  density  between  1.30  and  1.60  in  specific 
gravity,  consisting  largely  of  bone  coal  and  carbona-ceous  shale, 
which  forms  a middling,  or  secondary  coal  too  hi^  in  ash  and  siilfui 
to  include  in  the  clean  coal  and  yet  too  hi^  in  combustible  to 


• - 4 


•-4*>  ' i 


. ^ 


I I/H 

: e t‘  r^nltisjtw 


( 


'rtl^  '-S  , ■ •. 


) 


X 


0*  * 


177 

throw  away.  Hov/ever,  this  is  not  the  source  of  difficulty  with  this 
coal.  In  fact  the  sink  and  float  tests  shov/  that  there  is  an  un- 
usually small  percentage  of  this  material  present.  Visual  examina- 
tion and  specific  gravity  analysis  show  that  there  is  very  little 
free  dirt  of  high  specific  gravity  in  this  coal.  The  sulfur  must 
he  present  chiefly  in  some  other  form  than  pieces  of  clean  removable 
pyrite.  The  different  forms  of  sulfur  as  they  occur  in  the  raw  coal 
are  given  in  Table  41  below,  comparing  this  coal  v/ith  the  Clover  Run 
coal.  Fyritic  sulfur  was  determined  by  the  raethod  of  Powell  with 
Parr^,  and  organic  sulfur  by  difference. 

TABLE  41 

Forms  of  Sulfur  in  Spruce  River  and  Clover  Pam  Coal^ 


Total 

Organic 

Sulfur 

Fine  disseminat- 

Coarse  pyr- 

sulfur 

ed  pyritic  sulfur 

itic  sulfur 

Name  of  coal 

% 

^ of  to- 

% % of  to- 

% % of  to- 

tal  sul- 

tal  sul- 

tal  sul- 

fur 

fur 

fur 

Spruce  River 

2.48 

1.01 

40.  5 

0.71  28.6 

0.76  30.9 

Clover  Run 

3.  48 

0.71 

20.4 

0.50  14.3 

2.27  65.3 

As  shov/n  by  this  Table  an  unusually  large  proportion  of 
the  total  sulfur  is  present  in  the  form  of  organic  sulfur,  and  finely 
divided  pyritic  sulfur.  These  facts  and  the  very  low  percentage  of 
heavy  material  in  the  raw  coal  indicate  that  the  sulfur  is  widely 
distributed  and  that  there  are  very  few  concentrations  of  pyrite  in 
individual  pieces  sufficient  tc  bring  up  their  specific  gravity  and 

^Uniy.  of  111.  Eng.  Sxp.  Sta.  Bull.  111. 


178 


I 

make  them  removalDle  "by  washing. 

^2*  Indiana  No.  3 Coal.  A car  load  sample  of  this  coal 
was  examined  at  the  testing  plant  of  the  Deister  Concentrator  Com- 
pany. The  sample  consisted  of  screenings  through  a one  and  one-half 
inch  slot  screen.  Tests  v/ere  made  with  the  Deister-Overstrom  table 
on  a sample  of  5600  pounds  crushed  to  one-half  inch  maximtim  size 
and  on  a sample  of  6600  pounds  crushed  to  one-fourth  inch  maximum 
size.  Of  this  6600  pounds  6400  were  tested  on  the  commercial  size 
table  at  the  Deister-Overstrom  testing  plant  and  200  pounds,  a care- 
fully taken  sample  of  the  total  6600  pounds,  was  treated  on  the  lab- 
oratory table  at  Urbana. 

The  conspicuous  visible  impurities  in  the  rav;  coal  as  re- 
ceived consisted  of  shale  bands  and  clay  with  very  little  coarse 
pyrite.  The  shale  bands  were  very  largely  of  clean  grey  shale,  al- 
thou^  there  were  also  black  carbonaceous  sha,le  and  bone  coal  par- 
ticles. The  sample  used  for  the  0“  - v/ashing  test  carried  18,7 
per  cent  ash  and  3.92  per  cent  sulfur,  the  0”  - sample  analyzed 

8 

16.5  per  cent  ash  and  3.85  per  cent  sulfur.  The  specific  gravity  I 
analysis  of  the  0”  - feed  is  shown  in  Table  42.  This  shov/s  it  | 
to  be  about  an  average  coal  as  far  as  the  proportion  of  the  differ-  j 
ent  specific  gravity  increments  and  the  distribution  of  the  ash  are  l 
concerned.  The  sulfur,  however,  is  shown  to  be  very  uniformly  dis-  \ 


tributed  through  the  coal,  the  li^test  fractions  being  very  little  | 
lower  in  sulfur  than  the  heaviest  fractions. 


179 


} 


TABLE  42 


Specific  Gravity  Analysis  Indiana  No.  3 Coal 

0«  - Size 


Per  cent  of 

Per  cent 

Per  cent 

Specific  Gravity 

sample 

ash 

sulfur 

Lighter 

than  1.25 

68.  0 

5.4 

3. 19 

1.25  to 

1.30 

2,8 

8.9 

4.  12 

1.30  to 

1.  35 

5.4 

13.4 

3.83 

1.35  to 

1.40 

3.7 

15.8 

3.  86 

1.  40  to 

1.45 

2.8 

20.3 

4.  10 

1.45  to 

1.  50 

1.9 

24.9 

4.06 

1.  50  to 

1.60 

2.  6 

29.  5 

3.81 

1.60  to 

1,80 

2.3 

42.1 

4. 12 

Heavier 

than  1. 80 

10.  5 

71.  5 

6. 14 

TiiBLE  43 

Sink  and 

Float  Test  Indiana 

No.  3 Coal 

0"  - 

Size;  1.35  Specific  Gravity 

Per  cent  of 

Per  cent 

Per  cent 

Pro  duct 

sample 

ash  . 

sulfur 

Float 

78.8 

6.6 

3.  27 

Sink 

21.2 

59, 1 

6.40 

This  is  the  coal  which  was  used  for  comparing  the  results  | 

1 

securahle  with  the  laboratory  size  coal  v/ashing  table  with  the  work  | 
done  by  the  full  size  machine  in  commercial  operation*  | 


Fe>rcenT  'Y/'eld 


160 


min: 


\3ul-fui^ 


3uffur  Out^ 


curve. 


TABLE  44 


181 


Laboratory  Table  ¥/ashing  Test  on  Indiana  Coal 
Heads  16.5  per  cent  ash  3.85  per  cent  sulfur 


Sample 

We ight . 
Grams 

% of 
feed 

Cum.  io 
of  feed 

% ash 

Cum.  % : 

ash 

% sulfur 

Cum.  % 
sulfur 

» 

1 

4509 

11.6 

11.6 

10.20 

10,20 

2.  86 

2.  86 

2 

1860 

4.8 

16.4 

5,03 

8.60 

2.95 

2.  88 

3 

2015 

5.2 

21.6 

5. 14 

7.80 

3.  00 

2.90 

4 

1571 

4. 1 

25.7 

5.  32 

7.40 

3.  08 

2.94 

'5  , 

1137 

2,9 

>28.6 

5.64 

7.20 

3. 13 

2.96 

6 

2107 

5.  5 

34.  1 

5.77 

7.00 

3.  36 

3.  04 

7 

1999 

5.  2 

39.3 

6. 13 

6.90 

3.  28 

3.  10 

8 

2347 

• 6.  1 

45.4 

6.45 

6.80 

3.41 

3.  12 

9 

1863 

4.8 

50i2 

6.97 

6.80 

3.  48 

3.  13 

10 

2554 

6.  6 

56.8 

6.60 

6.75 

3.  40 

3.  18 

11 

3015 

7.8 

64.6 

8.20 

6.95 

3.  50 

3.  21 

12 

4720 

12.  2 

76.8 

10.85 

7.  55 

3.  64 

3.  27 

13 

3421 

8.9 

65.7 

18.  57 

8.70 

3.78 

3.  35 

14 

3026 

7.8 

93.  5 

45.05 

11.70 

4. 11 

3.  39 

15 

1798 

4.6 

98. 1 

78.00 

14.  80 

8.60 

3.  64 

16 

776 

2.0 

100.0 

58.92 

15.71 

15.65 

3.  88 

TABLE  45 


Indiana 

0"  - Washing  Test, 

No,  3 Coal 
Deister-Over Strom 

Table 

Wet  wt. 

Dry 

Product 

pounds  ^ 

1 moisture 

weight 

% of  feed 

% ash 

% 

sulfur 

Raw  coal 

6180 

9.0 

5624 

100.0 

18.  73 

3.92 

Washed  coal  5452 

18.  5 

4436 

77.0 

7.25 

3.  50 

(Coarse) 

Sludge 

( By  wt.  ) 

315 

( By  dif. ) 

283 

6.8 

34,  80 

2.  66 

Refuse 

1100 

13.6 

905 

16.2 

68.96 

5.93 

Sample  of 

vrashed  coal 

including 

sludge 

9,07 

3.49 

Same  by  calculation  from  sludge 

and  bin 

washed  coal 

9.00 

Time  27  minutes;  rate 

tons  per  hour 

.07 

check 

The  sludge  consists  of  fine  material  in  the  water  drain- 
ing from  the  washed  coal  as  it  is  elevated  to  the  Draining  Bin  (34), 
Pig.  33  , by  the  dewatering  drag  conveyor  (17).  This  was  sampled 
where  it  overflows  the  washed  coal  sump  16  to  the  overflow  sump  19. 


182 


Pennsylvania  Crusher 


17  Dewatering  Overflow 

Drag  Conveyor  7/a  ter 


34  Washed  coal 


Drai ning  Din 


I I 


sur.ip 


I 

y 


Centrifugal 

Pump 


y 

Dorr  j.hi  oicener 


/•giieri  can  Pi  Iter  ^ 

' 1 7/ater  Storage  Tank 


Fig.  33-flow-cheet  Deister  Concentrator  Company’s  Testing 


Plant 


1.” 


] 

-Jt 


&i.  ' #' 

t-i  ■■*. 


-V, : 


U' 

-'rr-^ 


9jtxS.nx  fXtv.  '■'-  • 


' -i'v  V 

-:  ■■'  ' ' i 


j 


K 


. k ' 'W  < .7 


*u 


l«'V 

* 


1^-  : ::^* 
r" 


-ii-c 

r"^'  ^ — "•■  --•-  ~ II  ■-  i 

i.-ou,^>  ' 4‘i 


T 

V 


i >'  ■ - r*.*  *A'  f 


" ■*»  '^' 


*i 


■ ?i:-' 


ukk*  ^rfl.'^i«;au 

' 


1 

t 


^ItTirSu 


X«3x;T  ii-Jr'ao'w 


't.  A 


I - - -y^ ;;;; 

' "■'  -^f^,  ’Vic\i 

► * ..  JT'.  i _ • 


u 


r-  — — . W ai»^ 


-*  t 


■ ;;  ,,,  “r-Ei X i.fl^  It !5;«.“v 


V r 0#  j ** 

| . jait'  L* 1 L. ; 


‘0^..  «*’,  4*(-.  ■ . ,_i  .,  , ■■  ^ 

® * '7T Aiicoi  tf-i”/)  lXfTt>oopC^t^>? u I 

il 


' . 1?: 


scHHarnaHEsesf^  ■ 


. )•  M 


183 


The  size  of  this  material  in  the  0“  - test  is  shovm 
by  the  screen  analysis  Table  46. 

TABhE  46 

Screen  Analysis  of  Sludge 


Size 

Per  cent 

Per  cent  ash 

On  1/64“ 

Through  l/32“ 

8,2 

25. 1 

On  65  mesh 

Throu^  V64« 

18.2 

28.1 

On  100  mesh 

Through  65  mesh 

21.  5 

28.8 

Through  100  mesh 

52.  1 

To  tal 

100.  0 

34,8 

The  loss  on  the  various  laboratory  tests  consists  of 
similar  material  which  overflows  the  settling- , cones  and  tanks  in 
the  laboratory.  This  product  varies  in  amount  and  composition  de- 
pending upon  the  nature  of  the  raw  coal  used,  the  type  of  washer 
used  and  the  method  of  handling  the  coal  after  washing  . The 
sludge  from  this  particular  coal  wa,s  exceptionally  high  in  ash  be- 
cause the  raw  coal  contained  a large  proportion  of  clay.  Analysis 
of  sludge  samples  from  two  other  coals  are  given  in  Table  47, 


TABLE  47 

Ash  Content  of  Washed  Coal  Sludge  Samples 


Coal  used 

Washer  used 

Ash  content 

No,  6,  Herrin,  Illinois. 

Campbell 

15.  5 

Ohio,  Brier  Hill. 

Be i s ter-Overs  trora 

13.  5 

The  sludge  is  ordinarily  higher  in  ash  than  the  coarse 
washed  eoal,  but  quite  often  lower  in  sulfur  content. 


to  n. 


■ ’ ''••  t'  f’ i i fri  Cil*I 


•i  rl  •■■%■  il./  i.i- 


184 

The  two  washing  tests  made  on  the  large  table  show  an  ash 
reduction  of  62  per  cent  and  a sulfur  reduction  of  11  per  cent  on 
the  0*'  - -i"  coal  and  an  ash  reduction  of  58  per  cent  v;ith  a sulfur 
reduction  of  12  per  cent  on  the  0“  - -i’*  coal.  This  shows  very  good 
work  in  the  removal  of  ash,  but  very  poor  results  in  sulfur  reduc- 
tion. 

This  is  a coal  which  is  very  amenable  to  v/ashing  as  far 
as  the  ash  is  concerned  because  a large  proportion  of  the  ash  is  in 
the  form  of  clean  shale  bands,  v/hich  are  easily  removed.  The  sulfur 
on  the  other  hand  is  very  difficult  to  remove.  Table  48  shows  the 
forms  of  sulfur  in  the  raw  coal  and  the  washer  products, 

TABLE  48 


Forms  of  Sulfur  in  Indiajia  No,  3 Coal 


Product 

To  tal 
sulfur 

Pyritic 

Sulfur 

Fine  dis- 
seminated 

Or 

S' 

ganic 

ulfur 

/*> 

ef 

fe>  of  to- 
tal 

Pyritic 

sulfur 

% 

% of 
to  tcol 

0« 

- raw  coal 

3,85 

1,99 

52 

1,43 

1.  86 

48 

0“ 

- washed  coal 

( coarse) 

3,  38 

1,39 

41 

1.99 

59 

0“ 

- -i-’*  washed  coal 
including  sludge 

3,32 

1,  40 

42 

1.92 

58 

0“ 

- raw  coal 

3,92 

2.  13 

54 

1.  48 

1.79 

46 

0« 

- !■"  washed  coal 
( coarse) 

3.  50 

1,4G 

41 

2.  04 

59 

0“ 

- washed  coal 

including  sludge 

3.48 

1,  53 

44 

1.95 

56 

Average  raw  coal 

3,88 

2.06 

53 

1.45 

1.82 

47 

Fine  disseminated  pyritic  sulfur  is  a comparative  term  which  vms 
used  in  this  work  to  designate  the  pyritic  sulfur  occurring  in 
fine  particles  disseminated  throu^  the  coal  to  such  an  extent  that 
it  cannot  be  removed  by  any  practicable  mechanical  process.  It  is 


‘ •<2*s£! 


' I 


D J 


_ . -'1-.  j 


.'r-fr  r‘ 


I 

*- 

I 


185 

arbitrarily  defined^  here  as  the  pyritic  sulfur  in  the  coal  which 
floats  on  a solution  of  1.35  specific  gravity  out  of  a representa- 
tive sanple  crushed  to  pass  a quarter  inch  round  hole  screen.  This 
shows  that  an  unusually  large  proportion,  55  per  cent,  of  the  sulfur 
in  this  coal  occurs  in  the  organic  form,  v;hile  the  Clover  Run, 

Spruce  River  and  Bon  Air  coals  showed  only  40.  5,  20.4  and  24.0  per 
cent,  respectively,  of  their  total  sulfur  in  organic  form.  In  the 
Indiana  coal  the  organic  sulfur  and  the  fine  disseminated  pyritic 
sulfur  combined  amount  90  per  cent  of  the  total  sulfur  in  the  raw 
coal.  This  eliminates  the  possibility  of  removing  any  appreciable 
percentage  of  the  sulfur  from  this  coal. 

These  tests  shov/ed  a concentration  of  organic  sulfur  in 

the  washed  coal  due  to  the  removal  of  inorganic  mineral  matter. 

This  is  a condition  which  might  be  expected  to  result  in  any  coal 

washing  operation  v^ere  an  appreciable  amount  of  shale  or  slate  is 

removed  as  refuse.  This  coal,  however,  was  the  only  one  examined 

with  which  such  a result  was  actually  secured.  The  raw  coal  con- 

any 

tained  a larger  proportion  of  clean  shale  than^other  used  in  the 
tests. 

Of  the  two  tests  the  0”  - run  showed  the  larger  yield 
of  washed  coal  by  4.5  per  cent.  This  ma^r  be  explained  as  due  to 
the  higher  percentage  of  ash  in  the  raw  coal  used  for  the  0*'  - 
test.  As  this  feed  contained  2.2  per  cent  more  ash  than  the  O’*  - :i‘* 
feed,  it  is  necessary  to  remove  approximately  four  and  a half  per 


^Distribution  of  the  Forms  of  Sulfur  in  the  Coal  Bed,  - 
Ynacey  & Fraser,  Univ.  of  111.  Sxp.  Sta.  Bull,  in  press. 


i 

i 


c 


i 

I 


i 


■V 


i 


186 


cent  more  refuse  in  order  to  produce  the  same  quality  of  washed 
coal.  This  indicates  that  crushing  the  coal  to  one-fourth  inch 
maximum  size  did  not  result  in  any  better  separation  on  this  coal 
than  was  secured  by  washing  at  0”  - size. 

The  efficiencies  secured  in  the  tests,  taking  float  on  a 
solution  of  1.35  specific  gravity  as  standard  washed  coal,  are  85 
per  cent  for  the  0"  - size  and  86  per  cent  for  each  of  the  two 
tests  on  0”  - coal. 


I 


187 


CHAPTER  VIII 
CONCLUSIONS 

33.  Sulfur  Re due tion»  The  washing  tests  showed  reduc- 
tions of  total  sulfur  content  in  the  No.  1 washed  coal  product  vary- 
ing from  a minimum  of  11  per  cent  with  the  Indiana  coal  to  a maxi- 
mum of  63  per  cent  with  the  Clover  Run  coal  washed  on  the  concen- 

the 

trating  table.  Tests  on^five  coals  examined  showed  great  variation 
in  sulfur  reduction.  Table  49  gives  a summary  of  the  results  se- 
cured on  the  different  coals  by  the  different  methods  of  v;ashing 
used. 

The  Clover  Run  coal  which  showed  the  largest  reduction 
in  sulfur  contained  the  smallest  proportion  of  its  sulfur  in  the 
organic  fom.  In  the  size  at  which  the  maximum  sulfur  reduction 
was  secured  it  contained  a comparatively  large  amount,  6.8  per  cent, 
of  material  heavier  than  1,80  specific  gravity  and  analyzing  23 
per  cent  sulfur,  while  the  proportion  of  natural  middling  between 
1.35  and  1.60  in  specific  gravity  amounted  to  only  12.6  per  cent. 

The  Indiana  No.  3 coal  which  was  the  most  difficult  of  1 
the  five  to  wash  as  regards  sulfur  removal,  contained  53  per  cent  | 
of  its  sulfur  in  the  organic  or  combined  form;  while  the  Bon  Air  | 
coal  also  difficult  to  desulphurize,  thougih  comparatively  low  in  | 
organic  sulfur,  contained  most  of  its  pyrite  in  the  form  of  finely  | 
divided  particles  disseminated  through  the  coal.  As  received  s.t  ! 
the  laboratory,  this  coal,  although  it  contained  4.87  per  cent  sul-  j 
fur  and  15.0  per  cent  ash,  showed  very  little  free  visible  impurity*! 
The  sink  and  float  tests  show  that  the  li^test  material  separated 
out,  namely,  float  on  solution  of  1.26  specific  gravity  amounting 


I 


0} 

+3 

(n 

0) 

E-« 

fcO 

•H 

Oi 

aj 


0) 

-P 

•P 

ON 

CO 

o o 

(H  •■-1 

^ -C-5 

cc5  O 

• Eh 

'O 

<u 


ClH 

rH 

CO 


-p  0 

rH 

G -H 

cd 

<D  -P 

0 

0 0 

0 

fn  fi 
<0  <13 

-P 

G 

G U 

0 

<U  G 

0 

0 Ch 

<U 

rH 

CO 

fH  G 

+ 

<13  CQ 
Ph 

'crJ 

0 

fi 

fi 

03 

1 — 1 

,cd 

03 

•H 

G 

•P  0 

G -H 

rH 

03  -P 

cd 

0 0 

0 

G 

0 

fi 
03  <13 

t5 

PM  fi 

0) 

fi 

-P  U 

G G 

cd 

<13  <M 

0 rH 

G 

1 — 1 

U CO 
<13 

• 

Ph 

0 

1 

fi 

1 — 1 

<l) 

•H 

>H 

-P  Pi 

rH 

G G 

cd 

03  <n 

0 

C3  rH 

0 

G 

Pi  00 
<U 

fi 

P 

cd 

<u 

ni 

N 

•H 

CO 

0 

a 

Td 

•H 

<13 

(H 

03 

"0 

po 

cd 

<u 

CO 

1=) 


cj 

o 

o 


O CM  CJNCM  CM  t>-CM 
rOCM  CM  CM  CM  CM  lr\ 


vO  ITN  vO  CM  CM  CM  CM 

^ 1—1  I — I rH  rH  I — I I — \ I — I r— I 


O OCO  CM  CM  UN  CM 
ONOO  •^C3D  C^UnC>- 


OnnO  UnUn 
CXD  O rH  CJN 

• • • • 


o rH  cjncm  m 

rH  O rorn 

• • • • • 


rH  rOmroCM  CM  «H 


rH  CM  CM  rH  CM  CM  ro mm 


mcjNONNOUNo  o 
• ••••«• 

vOsOvOnOOO  CJN 
CO  CO  l>~CO  CO  C?NCO 


UN'^  (JN  o 

• • • • 

NO  rHCO  t>- 
CO  0X0  CO 


CM  CN-CO  rH  t>- 

• • • • • 

CO  CM  mt>-UN 

CO  CTnCOCOCO 


o CM  CM  c>-co  CM  m m 
m CO  CM  m m ^ mvo 


CJNUN  O t>-  CM  CM  ^ rH 

oDcocoooomm 


C^nO  o o o 

>=d-  U\CM  CM  CM 


CO  coco 
CO  UNCJnOCO 


O mCM  rH  UN 
CM  CO  r — I I — I r 


o o CO  i>- 
OnO  UNmCM 


rH  rH  mmmCM  CM  rH  rH  rH  rH  CM  rH  CMrHmmm 


UnUNCJnOnnO  O O O UnCn-OUnUn  OmOUNCO 


CSNCO  NO  CM  CM  UN  m 
CO  Cn-OO  UN  l>-CO  NO 


sj-  •'ch  mNO  no  m rH  vo 

l>~tN-COCOUN  O-mCN-CO  t>- 


O 0(>-t>-t>-CO  OvO 
5N-  C ' GO  CO  CO  U\Un 


CM  CM  mmm 


rH  CO  CO  CO 

I 


rH  ^ 


S rH 

I 

\ = 
rH  O 


mmmrH  = rH 

I I I I Nt  I 

O O O O rH  o 


mOOCONO  rH 

un'^  '^UNm 


mmcM  CM  CM 


CO  m 

rH  mms  rH 


O O O rH  O 


ONC  O CM  UN  UN 
^ CM  CJNCOCO 


CM  CM  m m m 


'chco  CM  ^ 


fO  CO  (Hi — I I — I 

I I I I I 


o o o o o 


fl)  0)0)  (Ucyo©  G)dy«<i){D<u<u 

( — I I — I I — I I — I ( — I 1^  rH  I — 1 I — 1 I — I I — ! ( — I 

feO-Q  f-iOrQ  rO  ^^0  tiOrQ  M)  rQ  fit  bO  fi  ^fi  fi  fi  fi  fi 

•H  CS  -H  oS  c\5  -H  -H  cd  -H  ClJ  CtJ  -H  -H  cti  -H  n5  03  fi5  o5  cd 

Eh  “3  Eh  Eh  H3  —3  Eh  i— j Eh  Eh  h 3 Eh  H-3  Eh  Eh  Eh  Eh  Eh 


G 

G 

G 

G 

G 

G 

G 

"‘^4 

pc; 

fi 

fi 

U 

U 

U 

CO 

G 

G -H 

•ri 

•pH 

u 

Pi 

Pi 

U 

•H 

•rH 

<: 

< 

<D 

<13 

<U 

<13 

p« 

Pi 

!> 

t> 

t> 

> 

Pi 

Pi  G 

G 

G 

0 

0 

0 

0 

<D 

<13  0 

0 

0 

1 — 1 

rH 

rH  C>. 

( — 1 

fi 

fi  fi 

(fi 

0 

0 

0 ^ 

0 

Pi  Pi 

Pi 

mm<^ 

Pi 

<13  <13 

03 

03  • 

• • 

!>  I> 

!> 

> 0 

0 0 

•H  -H  -H  m 

fifififi 

■H  fi\ 

<13  <13 

03 

03  c 

G G 

C3  0 

0 

0 3 

3 3 

G G 

P ' — 

G -rH 

•H  -H 

Pi  Pi 

U CM 

Pi  TcS  xJ 

Pi  Pi  Pi  rH 

Pi  G 

G G 

CO  CO 

CO  — ' 

jO  IH 

HH  M 

rH  CM  m ^ unno  ctn  o rH  cm  m un^o  c>-oo 

rH  rH  rH  t — I rH  i — I I — I i — I I — | 


188 


189 

to  only  16,3  per  cent  of  the  original  raw  coal,  contained  1.28  per 
cent  of  pyritic  sulfur,  and  7*8  cent  ash.  This  shows  that  a 

part  of  the  pyrite  and  the  ash  is  distributed  through  the  lightest 
coal , 

The  West  Virginia  coal  from  which  it  was  also  difficult 
to  remove  the  sulfur,  contained,  like  the  Indiana  coal,  a large 
part  (40,5  per  cent)  of  its  sulfur  in  the  organic  form. 

Table  50  shows  the  forms  of  sulfur  in  the  five  coals  examined 
and  some  other  well  knov/n  iiiastern  and  Central  District  coals. 

Table  50 


Pyritic  and  Organic  aulfur  in  Various  Coals 


Dame  of  coal 

Total 

sulfur 

Per 

cent 

pyri tic 

Sulfur 

Pine  dissem- 
inated p^^’r- 
itic  sulfur 

Organic 

sulfur 

per 

cent 

Per  cent  Per 
of  total  cent 
sulf  ur 

Per  cent 
of  total 
sulf  ur 

Per 

cent 

Per 
cent 
of  to- 
tal 

Herrin 

2.70 

1.80 

67.0 

.92 

34.0 

0.80 

33.0 

Bon  Air 

4.87 

3.70 

76.0 

1.83 

37.6 

1.17 

24.0 

clover  Hun 

3.46 

2.77 

79.6 

.50 

14.3 

.71 

20.4 

V/est  Virginia 

2,48 

1.47 

59.5 

.71 

28.6 

1.01 

40.5 

Indiana  No,  3 

3.88 

2.06 

33.0 

1.45 

47.0 

1.82 

47.0 

Ivliddlefo  rk 

8.29 

1.99 

60,5 

• 77 

23.4 

1.30 

39.5 

(Benton, 111 inoi s j 

No,  12  W.  Kentucl<yl.48 

0.70 

47.4 

0.34 

23.6 

0.78 

52.6 

NO.  9 West  Ky, 

3.46 

1.65 

^7.3 

0.73 

21.1 

1.87 

52.5 

No  . 4 Indiana 

1,66 

0.89 

53.6 

0.77 

46.4 

( Vandalia ) 

pond  creek 

0.46 

0.13 

28.0 

0.33 

72.0 

Pike  CO.  Kentucky 

Blkho  rn 

0.68 

0.13 

25.0 

0.51 

75.0 

Letcher  Co.Ky, 

Pocahontas 

_ 0.55^_ 

0,08 

16.3 

0.46 

83.7  _ . 

Sulfate  sulfur  is  omitted  from  this 

table 

, As  in 

all  the  coals 

examined  it  amounted  to 

less  than  0.1  per  cent,  it  was 

con  si  dered 

negligible  in  amount.  In  Eastern  and  Central 

Di stri ct 

coals 

sulfate 

sulfur  is  ordinarily  pi-esent  in 

freshly 

mined 

samples 

only  in  very 

small  percentages. 


191 


TABLE  51 


Forms  of  Sulfur  in  Kaw  Coal  and  Washer  Products 


Total 

Pyritic 

Organic 

Coal 

Product 

sulfur 

sulfur 

sulfur 

Bon  Air^ 

Rav/  coal 

N 4.  87 

3.  59 

1.  17 

Table  washed  coal 

3.02 

1.84 

1.  18 

Table  refuse 

17.74 

16.77 

0.97 

Float  on  1.27 

2.  80 

1.  50 

1.  30 

Jig  washed  coal 

3.80 

2.61 

1.  19 

Herrin^ 

Raw  coal 

1.83 

1.04 

0.  79 

No.  1 washed 

1.81 

1.05 

0.  76 

No.  2 washed 

1.  56 

0.78 

0.-78 

No.  3 washed 

1.  57 

0.82 

0.75 

No.  4 washed 

1.  57 

.81 

0.76 

No.  5 washed 

2.33 

1.  57 

0.76 

Indiana  No.  3 

Raw  coal 

3.87 

2.06 

1.  81 

I-”  washed  coal 

3.47 

1.  53 

1.94 

washed  coal 

3.42 

1.40 

2.  02 

Illinois  No.  6^ 

Raw  coal 

3.29 

1.99 

1.  30 

V/ashed  coal 

2.25 

0.92 

1,  33 

These 

figures  show  not  only 

that  there  is  no 

reduction 

in  organic  sulfur  content  by  v/ashing, 

but  that 

in  some 

cases  there 

is  a larger  percentage  of  organic  sulfur  in  the  washed  coal  than  in 
the  raw  coal.  This  is  due  to  the  concen tration  of  organic  matter 
in  the  clean  coal  by  the  removal  of  mineral  matter  in  the  refuse.  \ 

3 

! 

This  effect  is  most  apparent  in  tlie  tests  on  the  Indiana  coal, 
which  contained  a large  proportion  of  clean  shale. 

This  limits  the  removable  sulfur  of  coal  to  pyrite,  seg- 
regated in  particles  large  enou^  to  concentrate  by  specific  grav- 

a 

ity,  and  gypsum,  in  such  coals  as  contain  gypsum  in  appreciable 


^Some  Factors  that  effect  the  \7a.shabili ty  of  a Coal, 
Fraser  & Yancey,  A.  I.  M.  E.  Bull,  153,  p,  1817. 

Ssamples  taken  at  the  Campbell  Table  Washery  of  the  Big 
Muddy  Coal  & Iron  Co.;  Nos,  1,2, 3, 4,  and  5 refer  to  standard  sizes 
of  washed  coal. 

^Average  of  a nuiaber  of  samples  taken  at  the  Washery  of 
the  U.  S.  Fuel  Co.  . Benton.  Illinois.^ 


190 

These  figures  indicate  t?iat  the  difficulty  in  removing 
the  sulfur  from  the  coals  which  have  been  designated  as  non-wash- 

i 

able,  namely,  the  Bon  Aii,  V/ect  Virginia  and  Indiana  Ho.  3 coal,  | 
is  due  to  the  presence  of  large  percentages  of  organic  sulfur  or  of  ! 
fine  disseminated  pyritic  sulfur  or  more  commonly  of  both  in  the  | 
raw  coal. 

It  has  generally  been  taken  for  granted  that  the  organic 
sulfur  of  coal  is  not  reduced  by  washing,^  The  results  secured  in 
the  experimental  work  of  this  study  substantiate  this  assumption. 
Results  of  the  determination  of  the  forms  of  sulfur  in  the  raw  coal 
and  washer  products  on  some  of  the  coals  used  are  given  in  Table 
51. 


^Bituminous  Coal  Washing,  L.  a , Harding  and  G.  R. 
Delamater;  Mines  and  Minerals,  Vol.  25,  p.  451;  Chemical  Control.^ 
of  Coal  V/ashers,  Bolling;  Eng,  & Min.  Joum,  , Aug.  29,  1908;  Coal 
Y/ashing  in  Illinois,  P.  C,  Lincoln;  Eng,  Exp.  Sta,  Bull.  ,69,  p.  12. 


G 


• 'n 

V 


( 


« 


e 


i 


i 


< 


( 


191 

quantities.  Table  52  gives  the  per  cent  reduction  in  pyrite  sulfur 
secured  on  the  coals  tested. 

TABLE  52 

Per  cent  Heduction  in  Pyritic  Sulfur 


Coal  used 

Machine 

Used 

Reduction 

Maxii^um 

secured 

in  pyritic  sulfur  % 
Maximum  secured 
with  a practicable 
yield  of  washed  coal 

Yield  1 
v/ashei 
coal 
% 

Herrin 

Table 

44.0 

41 

91.6 

Jig 

39.0 

39 

89. 5 

Bon  Air 

Table 

51.  5 

29 

86.6 

Jig 

28.0 

28 

86.9 

Clover  Run 

Table 

78.0 

64 

89.0 

Jig 

53.0 

41 

85.  0 

V/est  Virginia 

Table 

50.  0 

45 

75.0 

Jig 

34.0 

30 

91.4 

Middlefork 

Jigs 

52.  0 

52 

85.0 

Tables 

59.0 

59 

Indiana  No.  3 

Tables 

36.0 

38 

85.4 

Average  for  tables 

53.  0 

46 

Average  for  jigs 

40.0 

38 

In  drawing  conclusions  from  these  figues  it  is  essential 
to  take  into  account  the  fact  that  most  of  the  coals  tested  were 
submitted  for  examination  largely  because  they  presented  exception-  n 
aL  difficulties  to  sulfur  reduction.  Taking  this  into  considera- 
tion, it  seems  safe  to  expect  that,  v/ith  most  coals,  50  per  cent  of 
the  pyritic  sulfur  may  be  removed  by  vra,shing,  although  as  illus- 
trated by  the  Indiana  coal,  there  are  exceptional  cases,  where  a 
large  proportion  of  the  pyritic  sulfur  is  fine  and  dissemino.ted 
through  the  coal. 

Re duction.  The  reductions  in  ash  content  secured 
in  the  washing  tests  are  shown  in  Table  55.  The  greatest  reduction 
in  ash,  62  per  cent,  was  made  on  the  Indiana  Ho.  3 coal,  which  con- 


8-t  tl' 

sii  . .'  r\ 

i '7  ^ 

"I 

i ',  to:  '(' 


.iwi 


. ..  >;  > •• 

• - . 

I • ' .1 


N 

rH 

o 

192 

cti 

•H  4-> 

o 

-p  ^ G 

1 _ 

o 

o (u  a> 

rocvj  rH  o-,(XD  cv-o  rH  CO  C\JrOC\J(X)  CO 

d P4  o 

j ^ rH  rH  1 — ! OO  rH  OJ  rH  i — 1 r-H  rH  rH  ^ 

-d 

i 

U 

<u 

n5 

ft; 

C 

o 

•p 

1 — 1 

o 

^ ^ d 

rH  CO  \r\ONOJ  (>-C\)  O'NrHOO  O CO  O ITN  t>_ 

<u 

00  o;  (U 

• • •••  #••••  ••••  • 

<;  (4  o 

CO  CO  iH  rH  t>-  O OMTNvO  lr\  vO  ITS  ONCO  CO 

4- 

rH  ( — 1 1 — 1 rH 

a 

-d  -p 

COC3N  lr\00  OlTN-;!-  ONO  OJ  (>-CO  rH 

^ d d 

♦ # •••  •••••  «•••  • 

CO 

0)  (U  V 

\Ov£>  CO'^ON  C\jMDrHe0t>~  CO  OJ  COC^  ITN 

cd 

•H  O 

COCO  CO  ONco  cjNcoo  g'ncoco  CO  cr<oco  oo 

r ^ 

d 

o 

u^  o iT\  o o o irwxN  OJ  -it  o o 

•H  +3 

♦ •••••  •••• 

t — } 

d d 

CJNOCxj  «:t\r\coaNON  itnco  c\j  oxx)  rH  vocxjco 

cd 

o <u  <u 

CVJ^rHC\JC\iC\JrH^  CVJcOCMrHCM  C\J  cOvO  \r\ 

o 

d pH  o 

o 

-d 

to 

cu 

'd 

fd 

(D 

(U 

i) 

EH 

CO 

-p 

O-OJ  co-'t  COCO  CO  ONCJNCOvO  l>-  cOCM  (7^ 

cd 

rd  P d 

bO 

P" 

DO  (1>  (U 

t>-I>-COrHrHCr\rH'Lr\  OO  t>- ITN  lT\  H ICN  0^^ 

r; 

<;  ph  o 

rH  rH  1 — 1 rH 

•H 

1 — 1 

to 

• 

nJ 

o 

d +5 

IfNlTN  O^ONVO  O O O O t>- O lr\lr\  OCOOlT\ 

-H  p d 

o>  <u  <u 

CTnCO 'O  OJ CM  lr\  CO  'Lr\'4  ^ co^o  \OcOI>-rH 

ro  <u 

•H  Ph  O 

CO  O-CO  lrM>-C0 l>-C>-cocooo  t>- coc^co 

>H 

4^ 

<U 

rH  C 

■p 

P -H 

f — 1 

d 

o3 

cd 

<y 

£h  to 

o 

o 

c 

O CM  rH  rH  rH  00  rH  CM  CO  CO  CJVJO  CO  O-O-lTN  IO» 

o 

P 

•fH 

<u 

rH  1-T\^lr\ CM  O CMCMvO-sOvO  vOvOCOvO  vjO 

-p 

Ph 

rH  1 — 1 rH  i — 1 rH  rH  rH  i — 1 i — ! t — 1 i — 1 i — | « — ( 

o 

7i 

tJ 

to 

(D 

<{ 

cd 

0) 

rH  ^aoo)cx>  <H  ^ OD  ^ co^  ^ 

d 

<v' 

N 

1 S 1 1 \ 

bO 

to 

•iH 

= rH  COCOCOrH  = rH  rH  CO  CO  S rH  COCOrHrH  rH 

'd 

<: 

Ill’ll  till  1 

d 

rH 

rHOOOOOrHO  OOOrHO  OOOO  O 

to 

'd 

cd 

O 

C -d 

(0  <s)  <0  de^cDflj  doycudoa)  <u 

•fH 

d 

^ ( — f rH  rH  1 — 1 rH  rH  rH  rH  i — J i — 1 • rH 

cd  cd 

BO 

Jjopi  h04>  rQ  bO  bOrQ  bD4i  rQ  bO  bOpJ  bOrQ  4!  po  po  pj 

0 0 

o ^ 

•H  cd  -H  cd  cd  -H  -H  cd  -H  cd  cd  -H  -H  cd  -H  cd  cd  cd  cd  cd  cd 

0 0 

cd 

i-aEH-jC-HH-adEH-jEHEHi-a  -DEHt-jEHEHEHEnpiEH 

■si 

xi  xi 

CO  CO  CO 

d d 

P P P P 

^ d! 

CU  (D  <U  0 • • • 

to  m 

cjdd  d^-ppr-.  >000 

cd  cd 

d d d d -H  -H  -H  ro  -H  s;  !zi  d; 

{dcdfdr—  ccjpddPlrH  cc; 

PPP  CO  ' — dcdcd 

d d 

dd-H-H-Hppp—  podd  dddd 

CO  GO 

o 

•H.H<J<;<iJddd  dooo  c^cdcdcd 

P P 

to 

pp  t>  > t>  >ddd—  cs-rH-H-'^ 

cd  cd 

p 

ppdddooo'^  oPPPCM  p'd'od 

0 0 

ddOOOrHrHrHO-  rHP<pHp:<rH  pnd  dd 

0 0 

1 — 1 

jndjFq.cqoqooo— ' cj  xi  u:i  :n  coj-hhh 

cd 

• • 

o 

rH  CM 

o 

rH  CM  cO"^  ITnvO  t>-CO  <3^  0 rH  CM  CO  H IfNvO  t>-CO 

1 — 1 1 — 1 1 — 1 1 — 1 1 — 1 rH  1 — 1 ( — 1 1 — 1 

'■  " •' — — — 

193 

tained  a large  proportion  of  heavy  clean  shale.  The  smallest  re- 
duction was  on  the  Bon  Air  coal.  This  coal,  as  the  analysis  of  the 
raw  coal  shows,  contained  a large  percentage  of  ash,  hut  it  was 
largely  in  the  form  of  very  thin  hands  of  shale  interhedded  v/ith 
the  coal  and  the  disseminated  ash  of  hone  coal  and  light  carhona- 
ceous  shale.  The  effect  of  this  is  shovm  in  the  specific  gravity 
analysis  of  the  raw  coal.  Even  when  crudied  to  one-fourth  inch  maxi- 
mum size,  many  particles  are  part  dirt  and  part  coal.  Only  60  per 
cent  floats  on  a solution  of  1.30  specific  gravity  and  only  4.1 
per  cent  is  heavier  than  1.60.  The  remainder  35.9  per  cent  is  in- 
termediate in  deYisity,  and  consists  of  middling  coal  particles, 
high  in  ash.  Fig.  3, in  Chapter  III,  shows  the  specific  gravity 
analysis  of  the  Bon  Air  coal  compared  with  the  Herrin  coal  which  is 
much  more  amenahle  to  washing.  The  Bon  Air  coal  contains  36.1  per 
cent  of  material  Between  1.30  and  1.45  in  specific  gravity,  while 
the  fraction  Between  these  densities  in  the  Herrin  coal  amounts  to 
only  15.5  per  cent  of  the  total. 

Another  factor  which  affects  the  result  of  v/ashing  on  the 
Bon  Air  coal  is  the  hi^  ash  content  of  the  liglitest  coal,  floating 
on  1.30  specific  gravity  solution.  This  analyzed  10.1  per  cent, 
v/hile  the  corresponding  increment  of  the  Herein  coal  contained  4.64 
per  cent,  of  the  Indiana  coal  5.4  per  cent,  and  of  the  Clover  Hun 
coal  5.8  per  cent.  The  Bon  Air  coal  is  a typical  Boney  coal  con- 
sisting ma.inly  of  dull  coal  or  atritus.  Bone  coal  and  light  carBons.- 
ceous  shale.  As  received,  the  coal  sample  sho\ved  very  fev/  Bri^t 
coal  particles. 

The  Bon  Air  coal  v’as  the  only  coal  of  its  type  examined 
during  this  study.  Such  coals  are  common  in  the  Western  and 


t 


« 


\ 


X 


r#  h 


■ O ; > -i  i 


I 


f 


( 


< 


( 


c 


I 


194 

Alaskan  fields.  Tables  54  and  55  show  specific  gravity  analysis 
of  two  such  coals  which  contain  even  larger  percenta.ges  of  middling. 
In  washing  these  coals,  the  separation  between  washed  coal  and 
refuse  has  to  be  made  at  a much  hi£^er  specific  gravity  than  in  the 
avera.ge  Eastern  or  Central  District  coal  and  a higher  ash  fuel  must 
be  acceptabJ.e. 

TAEhS  54 

Specific  Gravity  Analysis  of  a Washington  Coal^ 

Number  2 Bed  0”  - 2^-’*  Size 


Specific  Gravity 


Per  cent  of 
rav/  coal 


Per  cent  ash 


Float  on  1.40 
1.  40  to  1,  50 
1.50  to  1.70 
Sink  on  1.70 
Total  sample 


Float  on  1.40 
1.40  to  1.50 
1.50  to  1.70 
Sink  on  1.70 
Total  Sample 


38.9 
14.  4 
16,7 

100.0 


Same  0”  - 3/8”  Screenings 


56,3 
8.  1 
14,  4 
21.2 
100.0 


11.9 
26.  2 
39.  2 

36.6 


8.8 

25.2 

36.2 

ISjJ, 

27.  5 


The  analysis  of  the  Washington  coal  shov/s  it  to  be  a 
mixture  of  clean  coal,  bone  coal,  snd  shale  with  only  a small  pro- 


portion of  free  particles  of  clean  coal  in  the  0”  - 2^-”  size, 


The 


0”  - 3/8”  size  shows  a.  much  larger  proportion  of  material  lighter 
than  1,40,  but  this  is  not  entirely  due  to  a more  complete  separa- 
tion of  dirt  particles  from  coal  particles  at  the  finer  size,  as 


^^^xperimental  v;ork  by  S.  R,  McMillan,  Northwest  Station 
U.  S.  Bureau  of  Mines*  ’ 


’X*iClk  X,'^  ' 


K 


■ f 

■i 


< 


:) 


i[ 


19  5 

the  average  ash  content  of  the  entire  sample  is  much  lower  than  in 
the  O'*  - 2^*^  unsized  coal. 

The  coal  is  washed  at  O'*  - 2'^'*  size  on  Blair  jigs  yield- 
ing 60  per  cent  of  washed  coal  with  an  ash  content  of  19. 1 per  cent 
and  40  per  cent  refuse  carrying  59.1  per  cent. 


T.'iBIJE  55 

Specific  Gravity  Analysis  of  a Nev/  Mexico  Coal 


Specific  Gravity 


Per  cent  of 
sample 


Per  cent  ash 


Ploat 

; on  1,25 

0.39 

4.4 

1.25 

to 

1.30 

23. 10 

7.4 

1.30 

to 

1,35 

29.59 

11.4 

1.35 

to 

1.40 

11.  55 

16.9 

1,40 

to 

1.45 

5.15 

21.3 

1.45 

to 

1,  50 

5. 19 

25.  8 

1.  50 

to 

1.  55 

6.81 

31.8 

1.  55 

to 

1.60 

3,  22 

36.  4 

1.60 

to 

1.65 

3.77 

40.1 

1.55 

to 

1.70 

2.  59 

44.7 

1.70 

to 

1.75 

1.98 

46.  1 

1.75 

to 

1.80 

1. 17 

51.9 

Sink 

on 

1.80 

5.  69 

65.  5 

It 

is  worthy  of  note 

that  of  the 

five  coals  examined  the 

Indiana  coal,Vvhich  gave  the  hest  results  in  the  way  of  ash  reduc- 
tion, showed  the  lowest  reduction  in  sulfur,  and  that  the  Clover 
Run  coal  on  which  the  greatest  reduction  in  sulfur  was  secured 
shov/ed  a comparatively  sma,ll  improvement  in  ash  content.  This  is 
contrary  to  the  general  statement  sometimes  made  that  the  sulfur 
follows  the  ash. 

On  the  Indiana  coal  tests,  the  very  fine  v/ashed  coal, 
designated  as  sludge  in  the  reports,  contained  a very  large  per- 
centage of  ash,  34.8  in  the  0*'  - test,  and  32.3  in  the  0“  - i*' 


196 


test.  This  indicates  that  the  fire  clay  was  not  separated  from  the 
coal,  hut  due  to  the  very  fine  size  of  the  particles  it  was  carried 

i 

over  the  washed  coal  discharge  side  of  the  table  with  the  light 
coal.  This  happens  to  a greater  or  less  degree  in  any  coal  v;ashing 
operation,  but  was  most  noticeable  in  the  Indiana  coal  tests  be- 
cause  of  the  exceptionally  large  percentage  of  clay  in  the  raw  coal. 
This  effect  is  explained  by  the  theory  of  settling  velocities, 
Chapter  III,  as  due  to  the  fact  that  the  ratio  of  sizes  in  the  feed 
exceeds  the  ratio  of  sizes  of  equal  settling  particles  of  coal  and 
shale  to  such  an  extent  that  the  smallest  particles  of  the  heavy 
mineral  settle  at  the  same  rate  as  the  largest  particles  of  the 
light  mineral.  While  it  is  well  known  tha,t  a ratio  of  sizes  great- 
ly exceeding  this  theoretical  settling  ratio  nay  be  handled  togethei 
efficiently,  it  is  often  observed^  that  the  very  fine  material  in 
the  feed  to  a coal  washer  is  not  cleaned. 

At  the  Middlefork  washer  ^vhen  the  coal  was  washed  at 
about  0”  - 1^-”  size,  the  fine  material  which  was  not  appreciably  | 

benefited  by  the  operation,  amounted  to  from  8 to  10  per  cent  of  j 

the  raw  coal  fed,  I 

Due  to  the  disintegration  of  friable  shale  and  clay  par-  |j 

ri 

tides  in  the  washer  the  fine  washed  coal  is  sometimes  higher  in  j 

I 

ash  content  than  the  corresponding  size  in  the  feed.  This  has 
evidently  taken  place  in  the  Indiana  coal  tests.  The  fine  material 
may  be  partially  separated  from  the  coarse  washed  coal  by  wet 
screening  or  by  the  use  of  a perforated  bucket  elevator  or  a de- 

^Coal  V/ashing,  Coal  Wendell,  An  article  to  be  published 
in  Coal  Age;  Coal  Washing, * Ernst  Frochaska, 

! 


’X 


\j  . ' 1".  ■' ^ 

.'-uj  iXJi  F 


A 9 * • 

f I ^ ^ 


O'*!  ♦.  •*rlC  JjiHj*  »i <=>-.*  .=•  o.: ’...;:  :.  .^  • 

..  i"i  a.-ii  . 0-  i-  oJ-  r'  ..' 

.-;v  ..iioo  ,t;i  ;■;•>/  TO  oj  I:-?'  " , 

- i .r.^;40*  .:;00  .:n.^XO?tI  0|-  •;  .,!  t .:O0X  J O.-  1 ^ om  ^ 

■ X‘^XO  1-  ^,1  L,.^wXJc;?>ovft  9^. 


;-«  A.I.lw  V OL' 


'.icn.f-’ .»aL"  V'  '>--ai.>Xq3?t  '>i 


«■  -9  . »:X 


...^  .'Ji  Ovi'r.cj  i»;  oXx.'r  ttL:  * ■>  .t  i’oal  oi  »i.'h  , Til  r 

''.'-»t » r ■ ;•  C.;  j'-:^.,  X-wpo  1<5  j l<;  oXiai 

'*-  ■ ’ ■*  ^ w*.- *■  r.^j  ■•-r  f .-tta  r*  «Xj-.  ■;.. 

’ - - '. 

■;  w o:/T'-q  j.  _ , fut:  , , -.rj-iro-®  XaTaJti.-;^ 

^ •*  •■!*.  .■’f-  '»  ',  *r  •“  ^ #r  «'  ••  ' 1"', 

■ ■ ^ . . ,.Cc.*'  iv.  id\ii 

.)  I I juO*  J O a .' j Ki.;.u^  T Tli;oS>OK'j»  \ [ 

;tx  orii’i  /\-;«v  -^fiovror  o . ai  ' ,;  ' uoi 

/ ;.jnro  30t.  «.  T3*'ia.?v.-  '^-wD  jj  5o;>‘: 

v'*A  ;j >•  , I-jjp  qoj'/»  *'».{s.‘.vr  .(10‘l*9lI)£'^I!  v-'f+  .Vs 

\:i*f  tcft  ftj.  - r.  ;-r  J r 

-TT-f  C'  o'  :V  ei  ' ' 


' ?^^^^  , irii  .:  - "C  itfoox. 

r;'." 

. «oq'S  0 J i>» 


.')'9  v-.r-x  3f;,J 

:-3  r»  . ■ ^r'r^itZ  'lo  rc..;Jvi'x:v>"ni<:a'*>  o-v  Ct4  c«Xi.<^ 

ni  .a-rQ'ia’  uo.:ij‘.  ,•.  ^>.ii  ‘xs£(i»jjw  tfjl.  -.'Jt  idiQ:  .t 

It.',  oic  , . a«'iu  ‘lil-rtoco®'; ':  ;.n  q.','«  ;icrj 

A*''-  - • snil  :>fu  , i.-,  o.‘  ! : .'u\ s b r’.'l  ‘ ■ .ij  ro.^fq  f{t>;4x:  t . ■ V ir.p 


^;y/'  XR-3d  A.yji-.o;  •ij'isoo  ii.it  ,;r;>v;  0^».T ,. Tcilr.,  »*!  • v 

J ^ 

'X.  ro..;ivaJ3  *> ji ^ i.'i 0 -i/r acf  ‘lo  asi/  firfj'  vi  'fc 


■ •,  ';  cJ  t*Xoi^TC;3  V ♦ '■  1 rt©7/  Xi.o''  X i 

. - -riooti  ^o-xa:\’.  ixiBxiV  lm.O  : .;^^  ,;x 


197 

watering  conveyor  to  move  the  washed  coal  from  the  collecting  sump 
to  the  storage  hins.  It  is  usually  not  high  enough  in  ash  to  he 
discarded  as  refuse,  hut  may  he  cleaned  by  rewashing  separately,  or 
may  he  used  separately  as  a secondary  coal. 

Pistjoss-l  hy  the  Washer  of  Particles  of  Various  Specif- 
ic Gravities.  As  already  pointed  out,  the  washahility  of  a coal 
depends  very  largely  upon  the  method  of  occurrence  of  the  impuri- 
ties. If  the  excess  ash  and  sulfur  are  concentrated  in  a compara- 
tively few  particles  of  high  specific  gravity,  the  coal  lends  it- 
self well  to  the  washing  process,  v/hile  if  the  impurities  are  dis- 
tributed throu^  a large  proportion  of  lighter  particles  the  coal 
is  difficult  to  wash.  Specific  gravity  analyses  of  raw  coal  sam- 
ples and  samples  of  the  resulting  v/ashed  coal  show  what  kind  of  par- 
ticles go  into  the  washed  coal  and  hov/  much  of  each  heavy  specific 
gravity  increment  in  the  raw  coal  is  removed.  Table  56  gives  these 
figures  for  each  of  the  coals  exarained. 


9 

E 

! 

5 


. rr  c :<  • > ■ r-a 


O'-’  t f .'•J  ^.r:;j,-i3  0c  \ ■:  '-.ictf  ^ 

' .V  /or:  ^ i J-  ^ . .,  > 

• • '•  • o v*-J  , 

* ' * l*b  . ■ ' • ^ M '»  : .>  * • 


> <■>  • T ■ 


J ,1  ' ~ ^ 

.•w  ' 


;.’■  -1 


, • ’ ■>  ■•' 


" ^ '>•■•■  « ; -,l 

i-'  a UQ^i' 

' ..  -:.‘l:i/b  on.'  fi.  . ;nf>orco  « .:>  tf  . 

-?r  a-tr-3E  *'  , C ' : oj>qi  ,:  liO.roiJ'Ifi  : S'*?!  -^XiV'- 

..'.  u : iTTi-q-j.-i  i c ir  'vlir'v,;  ^ ^ • .i*  <y*  : r^-.^  ■'ycj-- 

;-:oc-  ot:c- :a  noij  .:■.  qovn  .-•  'i 

‘ '.-  jo  : " V *\;l  ..^,.  yit\'  'I'l  ..  . - -- 

3.t'2f  .yo:..i  / ^0  * tL'£ic*i  ort?  ip  c-’.  colq 

- fift  ‘ 'rr  .,  r;  S,.,  ©^rri  (7.,  SrUl  ' ' 


* O'! d-i  :- -jji/rf ' vr  ,f 

r-v  0:  7r 


c;»y.':t  OC  " 

^ ■ ”'‘- 


• t.-'  ■ “ r 

a;  a:  ;....•;:  -;>T  \..  iv.:-;;  t,  ^ - 


^Ui'r  s 


• I,  OJ  ' . ‘t>  rio..-.o  *i£*l 


199 


These  figures  for  v/ashed  coal  in  each  case  represent  the 
cleanest  coal  secured.  In  some  of  the  tests  this  product,  desig- 
nated ITo.  1 coal,  amounted  to  too  small  a percentage  of  the  raw 
coal  for  the  production  of  a washed  coal  of  that  quality  to  he  com- 
mercially feasible,  unless  a certain  tonnage  of  secondary  coal  of 
considerably  hi^er  ash  content  can  be  disposed  of. 

In  the  table  tests  almost  all  the  material  heavier  than 
1.80  specific  gravity  was  removed  in  each  case,  leaving  a residual 
portion  amounting  to  from  0.4  to  0.5  per  cent  of  the  v/ashed  coaT. 
Generally  speaking,  there  v;as  a small  percentage  of  each  of  the 
heavy  increments  above  1.45  in  specific  gravity  in  the  washed  coal 
than  in  the  raw  coal.  The  percentage  of  middling  particles  lighter 
than  1.45  was  generally  no  lov/er  in  the  washed  coal  than  in  the 
raw  coal. 

On  the  Washington  coal,  washed  at  0^’  - 2^^*  size  v/ith  the 
Blair  Jig,  the  washed  coal  contained  3.4  per  cent  of  naterisil  heav- 
ier than  1.70  in  specific  gravity  and  a little  smaller  percentage 
of  middling,  from  1.50  to  1.70,  than  the  raw  coal.  There  was  a 

\ 

concentration  of  particles  lighter  than  1.  50  in  the  clean  coal.  | 

II 

Since  this  coal  is  so  radically  different  from  the  five  coals  exam- 
ined at  Urbana,  it  is  impossible  to  make  any  comparison  in  the  work 
of  the  machines.  The  figures  on  the  Washington  coal  merely  illus- 
trate the  fact  that  the  washing  of  such  a coal  presents  an  entirely 
different  problem  from  that  of  the  Eastern  District  coals.  The  ob- 
ject aimed  at  is  to  make  a separation  at  about  1.50  specific  grav- 
ity and  produce  a low  grade  fuel  from  an  otherwise  valueless  mate- 


rial. 


200 


Tatle  57  shows  the  distribution  made  by  the  washing 
table  of  the  particles  of  various  specific  gravities  in  the  rav/ 
coal.  The  figures  given  were  secured  in  the  0”  - 4'*'  test  on  the 
Indiana  coal  using  the  coinmerical  size  Deis ter-0 vers trom  ts.ble. 

An  unavoidable  error  v;as  incurred  in  making  the  specific  gravity 
tests  on  the  washed  coal  because  of  the  loss  of  very  fine  slime  in 
the  heavy  solution  used.  For  this  reason  the  value  given  for  sink 
in  1.80  specific  gravity  solution  is  too  low. 


57 


Specific  Gravity  Analyses  of  Products  of  the  0**  - 
V/ashing  Test  on  Indiana  No.  3 Coal 


Wa shed 

coal 

Refuse 

Raw 

coal 

Per 

Per 

Per 

Per 

By 

Specific  Gravity  cent 

cent 

cent 

cent 

analysis 

V/'ashed  coal 

of  of  plus 

raw  rav;  refuse 

coal  coal 


Lighter 

than  1,25 

79.3 

68.9 

— 

68.0 

68.9 

1.25  to 

1.30 

3.  6 

3. 1 

.2 

2.8 

3.  1 

1,30  to 

1.35 

5.9 

5.1 

.1 

5.4 

5.  1 

1.35  to 

1.  40 

3.6 

3. 1 

.2 

3.7 

3.  1 

1.40  to 

1.45 

3.0 

2.6 

4.2 

0.5  2.8 

3.  1 

1.45  to 

1.  50 

2.  5 

2. 1 

2.4 

0.3  1.9 

2.  4 

1.  50  to 

1.60 

1.  5 

1.3 

5.0 

0.7  2.6 

2.  0 

1.60  to 

1.80 

0.  2 

0.  2 

16.0 

2.0  2,3 

2.  2 

Heavier 

than  1.  80 

0.4 

0.4 

72.0 

9,3  10.5 

9.7 

Fig.  34 

shows 

graphically  the  distribution  made  by  the 

laboratory  ta,ble  of  the 

various 

kinds 

of  particles  as 

regards  both 

specific 

gravity  a 

,nd  size 

. For 

this 

work  a sample  of 

the  U'est 

Virginia 

coal  at  0 

- 3/8 

” size 

was  used.  The  data  was  secured  by 

making  a 

specific 

gravity 

analysis  on 

each  of  the  four 

products. 

No.  1 coal,  No.  2 coal,  No.  3 coal  and  refuse  and  screening  each 


1 


202 


specific  gravity  fraction  into  three  sizes:  0"  - i/Q”,  l/8”  - 

and  - 3/8«. 

■- 

The  area  of  the  large  square  in  the  figure  represents  the 
entire  coal  sanple  100  per  cent.  Therefore  the  percentage  relation 
of  each  product  to  tlie  original  raw  material  and  to  each  other  prod- 
uct is  represented  ty  the  relative  areas  on  the  graph.  In  addition, 
the  cumulative  yield  of  washed  coal  securahle  by  combining  products 
may  be  read  from  the  horizontal  scale  and  the  cumulative  percent- 

B.ges  of  float  in  each  product  may  be  read  from  the  vertical  scale. 

shov/s 

This  graph in  the  upper  right  hand  corner)  that  the  loss 
of  good  coal,  float  on  1.25,  1.30,  and  1.35  specific  gravity  solu- 
tions consists  almost  entirely  of  large  particles,  while  the  heavy 
particles  in  the  No.  1 washed  coal  are  all  smaller  than  one-ei^th 
inch,  as  shown  in  the  lov;er  left  hand  corner.  This  is  due  to  fine 
clay  particles  carried  over  with  the  washed  coal  near  the  head  mo- 
tion end  of  the  table  in  the  section  marked  No.  1 in  the  drawing 
Fig.  24. 

1 * 

In  all  the  tests  in  v/hich  a natural  feed  was  treated  cn  | 

! 

the  tables  and  the  special  equipment  for  dividing  the  product  into  | 

i 

a number  of  separate  parts  was  used,  a.  highier  ash  content  wr.s  se-  | 

\ 

cured  in  the  sample  discharged  into  this  No.  1 section  than  in  sev- 
eral sections  following.  This  was  especially  marked  in  the  test  on  | 

3 

\ 

the  Indiana  coal  where  the  product  from  section  No.  1 amounting  to  | 
11.6  per  cent  of  the  feed  carried  10.2  per  cent  .ash,  while  the  ma- 
terial going  over  between  this  section  and  a point  about  half  v/ay 
to  the  middling  corner  carried  only  from  5 to  6 per  cent. 

^Containing  all  sizes  from  a given  mo.xiirium  down  to  0. 


203 


36,  Efficiencies.  The  formula  devised  for  calculating 
efficiencies, 

I 

Actual  yield  x actual  ash  reduction 

Efficiency  — 

Stan  da  I'd  yield-^  x standard  ash  reduction 

was  applied  in  all  the  tests  made  and  was  found  fairly  satisfactory. 
For  comparing  the  results  secured  with  different  machines  on  the 
same  coal,  the  efficiency  figures  give  an  indication  of  the  rela- 
tive advantage  of  the  machines  used  for  treating  that  particular 
coal,  hut  when  the  operations  to  he  compared  are  on  radically  dif- 
ferent coals,  the  comparison  of  the  machines  hy  the  efficiency 
figures  is  uncertain,  because  the  completeness  of  the  separation 
secured  depends  upon  the  nature  of  the  coal  as  v/ell  as  upon  the 
process  used.  The  efficiency,  as  calculated,  depends  upon  the  pro- 
portion of  heavy  material  taken  out  as  a percentage  of  the  total 
amount  of  heavy  material  occurring  in  the  raw  coal.  The  figures 
of  Table  57  indicate  that  the  average  percentage  of  sink  particles 
retained  in  the  washed  coal  is  a more  or  less  constant  minimum 

rather  than  a certain  proportion  of  the  amount  occurring  in  the  | 

5 

k 

original  raw  coal.  For  this  reason  a coal  like  the  Indiana  No.  3,  » 

which  contains  a large  proportion  of  heavy  removable  refuse  will  j 

sliov/  a higher  efficiency,  as  calculated,  than  such  a coal  as  the  | 

I 

V/est  Virginia  sample  which  contained  only  a very  small  percentage 
of  sink  particles.  This  may  also  explain  the  hi{^  efficiency  of  the 
jig  operating  on  the  Washington  coal  which  shows,  by  calculation 


^Yield  by  sink  and  float  test  on  the  solution  used  as  the 
permissible  bath. 


••  i 
> 


-i.  L»  .i  ' ' i ; 

I-.'  >■  >j,; 

V V j £.1.'  • ■ 'j 

C :\SZf‘i-V  t 
''  ■'  / Oi  i 


. ..  . . . 

< Zl  X.  . •.  . ..I’  .... 


*‘~4  #fcjQflk  rj:.-:;  '.,j  n*.  'j 

' 


ii  1 

j"  f ^ ^ 


;..  U • .r.  r 


I ■^-. 


90 


svi:^  : .i-::i  n . v:.'Aoiuxn« 

■:n._  b'.-ns  ---snu  ;"  'r/ r ; 

•'•  • ■ • '•  ■ ji.  ' -iO  VV  ‘ 

' ‘ n^oii  *rf:  , ,,.-j 

■ r.*  :^.  ■ ^ --^-v  , i T? 

'• 

f.  ; X«;oc  '.o  . :r?nx 

. 1-"-  , * . •>-':. r 

' . * ‘ .1  . _ i"  ■ ?«  ii-l  l^V 

■ -■'  . .'  .•-  '■■  . n".*? . 561  V 

“ f \ - 1 V .’' . . fjii.  '.'w  *irv ! T'J  'ji.  'S<  * ^ 


■I- -i-  l 


A 


» ,r 


• X 


; ^<.'6  1 - ■;  'ii 

. '•m'Qi.'X  Jf  r.” 


■f  ' 


I r'.-.'.i  .' 

rr: 

. ' i'C 


N 


1*^ 


•V 


« 


riw:‘  .O’.  iijL/U  *I«  , .*'..;.'5:  t-\- 


' •*■"*  k '-■  fi’.  A'  * !>•  1 x.^’^r 


tv  -A 


on 


204 

from  the  above  formula,  an  efficiency  of  97  per  cent  while  the 
washed  coal  contains  3.4  per  cent  of  the  heaviest  material  as  com- 
pared with  0.4  to  0.5  per  cent  for  all  the  other  coals  reported. 
Table  58  shows  the  efficiencies  secured  in  the  tests. 

t;\ele  58 


Efficiency  Figures  For  the  Washing  Tests 


Per  cent 

ash_.  _ ..  . 

Yield 

Coal 

Size 

Machine 

Raw 

Washed 

Float 

Float 

Washed 

Effi- 

used 

used 

coal 

coal 

coal 

coal 

coal 

ciency 

Herrin 

^1, 

1” 

JiS 

11.0 

7.7 

5.6 

82.  0 

89,  5 

67 

Herrin 

- 

^11 

Table 

14.2 

7,2 

5.4 

82.0 

78.  5 

76 

Eon  Air 

0" 

- 

3/S”  Jig 

15, 1 

13.  1 

12.  1 

92.0 

SC,  6 

56 

Bon  Air 

Q» 

- 

3/8**  Table 

15.  1 

13.3 

12. 1 

92.0 

86,6 

56 

Clover 

Run 

Clover 

o» 

- 

1'* 

Jig 

12.8 

9.8 

5.4 

74.  5 

78,0 

44 

Run 

Clover 

^1! 

— 

1'* 

Jig 

14,1 

11.4 

6.2 

65.0 

85,0 

48 

Run 

O’* 

- 

^11 

Table 

10.4 

6,2 

4.8 

85, 1 

82.  5 

74 

Clover 

Run 

West 

0" 

- 

3/a 

"Table 

12,8 

7.9 

74.7 

80 

Virginia 

West 

g« 

— 

f « 

Jig 

6.8 

5.3 

4.0 

91.2 

84,0 

48 

Virginia 

West 

— 

Jig 

6.9 

5.  5 

4,0 

90.0 

83.  5 

45 

Virginia 

o« 

3/8*»  Table 

6.8 

4.8 

3.8 

93,3 

74,  5 

54 

Indiana 
No.  3 

0” 

Table 

18,7 

9.0 

83.8 

85 

Indiana 
No.  3 

O'* 

- 

Table 

16.  5 

8.  5 

87, 1 

86 

Considering  each  coal  separately,  washing  on  the  table  at 
fine  size  showed,  as  a rule,  a sli^tly  higher  efficiency  than 
jigging  at  larger  size. 

The  low  efficiencies  secured  in  the  jigging  tests  may  be 
due,  in  a measure,  to  the  difficulty  in  adjusting  the  operation 
properly  in  short  tests  of  this  kind.  It  is  very  probabl.e  that  un- 


205 


der  continuous  operation  the  specific  gravity  separation  can  he 
more  nearly  duplicated.  The  operation  of  the  table  can  be  brought 
to  the  correct  adjustment  much  more  quickly  because  the  material 
being  treated  is  spread  out  on  the  table  deck  in  full  view  of  the 
operator  and  every  stage  of  the  separation  being  made  is  under  ob- 
servation; while  for  the  adjustment  of  a jig  the  operator  must  de- 
pend entirely  upon  an  examination  of  the  products  after  they  are 
discharged  from  the  machine.  This  is  a condition  v/hich  even  in  con- 
tinuous operation  militates  against  the  efficiency  of  the  jig. 

The  fact  that  coal  of  jigging  size  usually  contains  more 
middling  particles  than  the  sane  foal  crushed  to  finer  size  for 
table  treatment  also  makes  it  more  difficult  to  make  a close  spe- 
cific gravity  separation  v^rith  the  jig.  This  was  especially  true  in 
regard  to  the  tests  on  Clover  Bun  coal  and  accounts  in  a large 
measure  for  the  low  efficiencies  on  the  jig  tests  with  this  coal. 

The  preliminary  sink  and  float  tests  showed  conclusively  that  in 
the  larger  sizes  an  efficient  separation  at  1.35  specific  gravity, 
the  solution  which  gave  the  desired  quality  of  float  coal,  could 
not  be  made  without  a very  large  loss  in  the  refuse,  resulting  in  a 
prohibitively  low  yield  of  washed  coal. 

These  tests  indicate  that  tabling  at  fine  size  will  pro- 
duce a cleaner  washed  coal  than  jigging  at  larger  sizes.  This  ap- 
plies especially  where  the  problem  is  to  remove  the  sulfur  from  a 
coal  in  which  it  occurs  as  thin  fla.kes  and  veinlets  of  pyrite.  In 
the  tests  on  the  Clover  Run  coal  which  was  of  this  type,  the  wash- 
ing table,  treating  a feed  of  0"  - 3/8“  size,  produced  a washed 
coal  of  1,53  per  cent  sulfur,  while  the  jigging  test  on  0“  - 1” 
feed  gave  a smaller  yield  of  washed  coal  analyzing  2.02  per  cent 


206 


sulfur.  On  the  West  Virginia  coal, which  contained  70  per  cent  of 
its  sulfur  in  the  organic  and  fine  disseminated  pyritic  forms,  a 
small  No.  1 coal  product  was  separated  out  vdaich  analyzed  1,6  5 per 
cent  sulfur  and  was  sufficiently  clean  for  tt-ie  purpose  desired,  al- 
though of  too  fine  size.  This  greater  effectiveness  of  the  table 
over  the  jig  in  reducing  the  sulfur  content  is  due  more  to  the  fact 
that  fine  crushing  frees  the  pyrite  particles  from  the  coal  parti- 
cles than  to  a more  perfect  separation  between  particles  by  the 
table;  althou^,  as  the  efficiency  figures  indicate,  the  latter  con- 
dition is  probably  true  in  s measure. 

In  preparing  coal  for  coking,  where  the  fine  size  of  the 
washed  coal  is  no  disadvantage, the  table  may,  therefore,  be  used 
to  advantage.  In  preparing  coal  for  fuel  the  advantage  of  more  ef- 
fective cleaning  is  probably  more  than  offset  by  the  disadvantage 
of  fine  size,  unless  fine  coal  is  required  for  some  special  use. 


